I was an active contributor on SO in the early days - it was fun to help folks out, and it was often the only way to get help when I needed it myself.
For me, it stopped being a place I wanted to visit when they made the decision to close any question that they didn't deem a perfect fit for their vision of SO. There was certainly some value to that around the edges, but the policy ended up being enforced so strictly that many interesting topics their audience would have found valuable were declared out-of-bounds. Questions I wanted answers to - and that were getting good answers! - would get closed, and so would interesting questions that I wanted to try to answer.
I tried a couple times to push back gently, and got piled on each time.
It stopped being fun, so I stopped going there. Shrug.