What rapid changes have we seen lately? The change in that person's comment has been in the making for over a hundred years. The first thing I personally can think of (in the context of America, as one of the last Western countries to accept GLBT people, not in the context of the wider world, which has been accepting for much longer than America) is American GLBT communes in the 1780s.
Given where we are in GLBT acceptance, it seems like, if anything, this was one of the slowest-changing social norms of all, and one that more than a few generations were pushing for before the ones that are currently here.
I think the gutting of middle America is a big part of it. The most talented people are forced to leave for the coasts to make the most of their capabilities. This hurts both the leavers (like me) who have to built roots from scratch in their new home and hurts the remaining population due to the resulting brain drain. The us-versus-them attitude is then worsened by classist attitudes toward those entire areas based on the population who remain by my fellow “progressives” who will endlessly mock “flyover states” and anybody in them.
Albeit I didn't know about those communes, but I think LGBT acceptance was extremely rapid. The only other change I'm ready to compare it to was slavery and black civil rights: consider that the first state to legalize same sex marriage was Massachusetts in 2004. Over the next 11 years, we reached 37/50 states total, and then in 2015 with the supreme court decision we reach all 50/50.
For civil rights: we had slavery since the arrival in 1619 (which is the date I hear); we get the emancipation proclamation in 1863 ending slavery; but there are still Jim Crow laws until the civil rights and voting rights acts in 1964 and 1965.
To me that makes the road to LGBT acceptance sound extremely rapid, but someone with more awareness of historical trends in the US should put these into context. In particular when might we say various struggles began seriously, or entered the public consciousness.
That's framing things from a legal perspective, but even then there are some key legal steps you're missing (and this isn't conclusive at all):
Beating someone based on sexual orientation was recognized as a hate crime first in 1984 at the state level. 1995 and 1998 were when Clinton banned discriminating against gays at the Federal level via Executive Order.
1996 was when Clinton signed DOMA, which is the reason legislation stopped for so many years. Though lately he's tried to conceal that, it prevented GLB rights from advancing for many years. It was in response to states legalizing same-sex marriage.
1993 was when GLB people were first allowed to serve in the military.
1993 was also when Hawaii found bans on GLB marriage unconstitutional (at the state level).
1992 Colorado passed Amendment 2 which specifically forbade Colorado state, county or municipal governments from recognizing homosexuals as a protected class.
1998 Oregon makes GLB people a protected class, preventing people from discriminating against them on the basis of sexual orientation.
1984's National Gay Task Force v. Board of Education partially gutted a law that allowed schools to fire teachers on the basis of sexuality. (NGTF was founded in 1972.)
1977: GLB allowed to work for the IRS and foreign service, GLB activists for the first time invited to the White House.
1960s-1970s: Gerald Ford, for all of his faults, being the first 1900s President to really be pro-GLB.
1970 featured my favorite Nixon quote: "I can't go that far; that's the year 2000! Negroes [and whites], okay. But that's too far!" By 2000, as you can see, things were not much better.
1950s, 1960s & 1970s saw it come into general awareness; lots of protests, including Stonewall.
1901 saw DC make it harsh again; no felony, but a lot larger a fine, no imprisonment.
1892 basically decriminalized it in DC; you get a fine and you pay bail.
1807 saw Indiana make legislation to lessen the punishment for it (although it was the first to be for both genders); 4 years max, a fine, and a felony.
1801 had Maryland making perhaps the laxest law on sodomy ever: <7 years of punishment, the act of cleaning one's town, no imprisonment.
Jefferson failed in 1779 to liberalize his state's punishment for sodomy, but that's probably the first act of legislation trying to go easier on homosexuals. Virginia later passed (I think before 1800) a law that limited the punishment to 10 years.
George Washington brought in a general who was being persecuted in Germany for being homosexual shortly after we won the Revolutionary War, he was never punished, got pension, etc.
No states legally recognized same-sex marriage before 1996. Same-sex marriage was a relatively new controversy at the time, but one major reason for that was because Republicans were able to use the issue to motivate their base by trying to preemptively curtail it. Furthermore, DOMA was passed with a broad enough majority that any veto would have been overridden anyway. Picking a fight on DOMA would have only further motivated efforts at the time to prohibit same-sex marriage with an amendment to the US Constitution.
The 1993 ruling in Baehr v. Lewin simply remanded the case to a different count; it did not "find bans on GLB marriage unconstitutional". In fact, by the time the final ruling happened (as Baehr v. Miike), the Hawaii constitution had been amended anyway.
1992 Colorado passed Amendment 2 which specifically forbade Colorado state, county or municipal governments from recognizing homosexuals as a protected class. The amendment explicitly allowed the government of Colorado to be used to discriminate against gay people.
That's my only quibble with your list, other than Bill Clinton also signed Don't Ask Don't Tell.
Reduced religiousity, and reduced family formation. Church membership was stable from 1938-1998. But from when Google was founded to today, it dropped from 70% to 50%. https://images.app.goo.gl/4b5wG27yprR4bfZg6
Also, it’s probably not accurate to say that America is one of the last western countries to accept LGBT people. Same sex marriage was legalized nationally around the same time in the US as in Germany and the UK. A number of western countries still don’t allow it, including Italy, Greece, Switzerland, Czech Republic, and Poland.
Poland and the Czech Republic aren't Western, they're Slavic. The USSR wasn't Western, nor are the offshoots of the USSR.
East Germany stopped prosecuting against GLB in 1957, and homosexual activity was officially decriminalized in 1968. 1980s Berlin literally had state-owned (again, East German) locations that were explicitly for GLB activity.
Took a bit longer for West Germany, but acceptance happened in the 1980s and in 1990 West Germany allowed GLB to join the military.
Same-sex couples have had (most of) the same legal rights as married couples since 2001 in the combined nation, I'm pretty sure, though I could be off a year. They were also allowed to adopt pre-2010, but I can't remember when.
It wasn’t not really much different in the US. You just have to remember it’s a state-by-state issue for the most part. Same sex intercourse was decriminalized in Illinois in 1962. Through most of the NE, Midwest, and west coast by 1970-1980.
The word "rapid" is doing a lot of work in both yours and GP post. The fact is that a hundred years is a very short amount of time if you really think about it. My grandfather was born in 1913, and if Thoreau had lived a long life–and had been connected to my family–he could have looked at my grandfather's eyes as he held him in his arms.
You're mentioning a specific example, but really think about it. In the span of three, maybe four generations, society has changed abruptly. The invention of trains and cars, the remaking of cities and countries, the internet. Before the industrial revolution, generations of families could live and die in the same place, following the same customs and traditions.
Nowadays, we, influenced by the internet in part, can barely imagine a future because the situation looks so unstable. We don't have the comfort of knowing what even the next decade is going to look like.