I hear they're drowning in AI bots. I guess a fair amount of people also don't mind talking to those.
But SO was never intended to be a place where people "talk to each other". It was specifically intended and designed (sort of; the design was faulty) to avoid chatter because that gets in the way of others coming by later and finding a question and reading its answer.
Yeah, the place could be very hostile, but that hostility didn't crater questions before ChatGPT was released.
Also, they had the usual incentives to avoid doing things that would slow down initial growth. They were trying to build a community, and they definitely succeeded at that.
It took until the "middle times" for people to really develop an understanding of how questions for a Q&A site are supposed to look. And then the rest of the time was spent trying to convey those standards accurately, caught between the usual archetypes of angry forum users, in a place that was not supposed to be a forum.