Using "chairman" to describe a position implies that it's occupied by a man. And the writing may need to be revised for someone who is female who doesn't want to be referred to as a chairman or mailman.

Using "patriarchy" to describe a specific male-headed familial structure is for the purpose of criticism is descriptive, just like "matriarchy" is. Of course, it can be misused, like in the cases you pillory.

> No, that's precisely "an indefinite, hypothetical or otherwise vaguely described person (e.g. the perpetrator of a crime before being identified)".

I thought you were drawing a different distinction; it's definitely the personal singular they. That exact type of usage is when I use "they" to refer to a person of indeterminate gender, e.g. someone to be hired.

> Within the last quarter-century or so? Despite the readily available evidence of other people of the same gender doing that thing?

Much less within the last quarter-century... in part because all of the style guides about this stuff changed about 40 years ago, when I was a small child.