> but eventually I concluded the rule-of-thumb "don't use derogatory metaphors about other people" is often not hard or that big of a deal
This is simply untrue.
A couple of decades ago, one could use the hyperbolic euphemism “I would of course be lynched for suggesting such a thing”, completely devoid of any racial animus, because human history is of course rife with instances of lynchings of people of all skin tones and racial origins. But today, a concerted effort has been made to “brand” “lynch” as a term that is “racist against black people—black Americans specifically.” There is no historical reason for this to be the case. The ADL was founded after a Jewish man was lynched because the lynch mob believed him to be guilty instead of a black man, for instance!
Just because a given term or metaphor or euphemism isn't considered offensive-toward-a-certain-class-of-people today, doesn't mean that somebody won't invent a reason for it to be considered to be such tomorrow.
This is simply untrue.
A couple of decades ago, one could use the hyperbolic euphemism “I would of course be lynched for suggesting such a thing”, completely devoid of any racial animus, because human history is of course rife with instances of lynchings of people of all skin tones and racial origins. But today, a concerted effort has been made to “brand” “lynch” as a term that is “racist against black people—black Americans specifically.” There is no historical reason for this to be the case. The ADL was founded after a Jewish man was lynched because the lynch mob believed him to be guilty instead of a black man, for instance!
Just because a given term or metaphor or euphemism isn't considered offensive-toward-a-certain-class-of-people today, doesn't mean that somebody won't invent a reason for it to be considered to be such tomorrow.