Largely comes from shit heads who use open VC, especially on FPS games, to say heinous shit, given that it’s pseudonymous and they’re not likely to face real consequences from it.
It’s less of a thing these days simply because the novelty has worn off and pseudonymity is less of a protection than it used to be, since a bad reputation in an online community actually means something if you spend a lot of time there.
But, a loud obnoxious idiot shouting slurs or spamming them in text chat tends to paint a whole community in a bad light, creating the stereotype.
I’m constantly getting bot checked these days because I do a lot of stuff when casually browsing to prevent being fingerprinted and tracked between sites. I wonder how often they just mark anyone not making them selves easy to identify as a bot.