I know exactly when I permanently stopped contributing to the site: it had been a few years since I happen to have something worth posting a question about, but for once I had a niche question about a popular-enough framework it was worth a shot.
A guy replied with a generic wall of text that had nothing to do with what I had asked, merely contained some of the keywords I also used.
When I politely pointed out it's not what I asked and reformulated in case he merely misunderstood, he got mad that I had refused to just give him the points.
He got extra mad when I figured out the answer on my own and posted it as answer in case others stumbled on the same issue, so he tried to edit my answer to make it look irrelevant.
Unfortunately for him, he didn't realize I also have enough points to edit it back, so he gave up and deleted all his comments to make it look like I'm talking to nobody, then went to downvote a bunch of my older posts.
And the sad part is that guy initially seemed well regarded in our small community, kinda killed my motivation to contribute to the site again after that. Plus I usually always find answers on my own, and anything I can't figure out on my own is so niche it would be pointless to ask.