I think a lot of it is also onset by the modern internet (twitter, instagram, tinder, etc.), where snap judgements of people are made based on a very limited se

I think a lot of it is also onset by the modern internet (twitter, instagram, tinder, etc.), where snap judgements of people are made based on a very limited set of information - typically a picture, and a short bio. In those cases, concise and effective social signaling is extremely important; and that's just what bios like "husband, father, christian, ruby programmer, beer lover" accomplish. In a few words, you've just made yourself relatable to a high proportion of people who will read your profile . If your bio is more niche, like "bassoon player, atari 2600 collector", then you've put up an easy filter to only attract the attention of the very specific group of people you care about. Particularly when taken in a romantic/sexual context, it makes it much easier for one with niche preferences to find people whose preference overlap theirs. There's another dimension to it, where these labels become aspirational. Perhaps I only play the guitar once a month, but really want to think of myself as a guitarist; in which case, just putting it in my bio gives it some air of legitimacy.