I've see authors, actors, scientists, artists, musicians, journalists and people of all stripes (and not all from "tech circles") on Mastodon.

Ironically, most complaining I've seen about the technical hurdles of joining Mastodon have come from techies on HN. Meanwhile Stephen King, a nearly 80 year old author who probably still uses a rotary phone and manual typewriter, managed to figure it out.

Or more likely find someone to figure it out for him but still.

Some content producers/personalities are certainly using these services, but the content consumers aren't common outside the tech circles.

Agreed. I've never been on Mastodon, because there is no reason for me to bother (I did hear about it). Threads? I DID hear about it and I'm actively refusing, because if I need Threads account, it's bound to my Instagram account and if I don't like it and resign my IG is gone. Meh, no need for that.

But same applies with Discord for me. Why would I be there? Why companies expect me to contact them via Discord? Yo, gimme wiki, or answer email. I don't need some chat-thingy/Slack/Discord.

Edit: Why don't we have email, nntp and IRC anymore? Just build stuff on it, don't reinvent.

Think I've come across two links to mastodon in my life (probably here on HN), and have never encountered threads (I do live in Europe).