Decades ago I visited a popular commercial home audio enthusiast site to get info and chat about our hobby. They had sections for your particular question/interest, and it was fun and educational, but as more people found it the conversations became...you know. Then one day a moderator started posting about an independent place to chat...without saying what or where or how, just something like "meet us outside". You kinda had to know, or get invited, or something, but I found my way to it and it was chock full of smart, funny, audio sick people, who were so self-effacing about their hobby....well it was just fun and for a year or so there were no rules at all. We got so comfortable posting anything about anything with no consequences (the insiders were really good about seeing a line...those who crossed it just disappeared) that we'd forget you can't post like that, say, on places like this. Then the riff-raff found it and ruined it. Regression to the mean.
Why do these visitors do this? I think it's the juice they get, that little endorphin buzz of posting something they think will upset people or get them attention.