And yet StackExchange has survived to rule all over programming forums. Probably largely because the moderation is extremely heavy and kept heavily on topic...
I don't think so. SO/SE have won because they've always been honest - they provided Q&A service without upselling you bullshit, spamming you with ads or forcing you into paid plans. That eventually led them to #1 spot in Google for everything programming. I don't see how heavy-handed moderation could help here; if anything, half of the questions I search for are marked as duplicate / not relevant / etc. Basically, I can't imagine what question can be relevant to SO anymore...
The ones you are looking up in the documentation yourself?
At least that's what I've noticed: I had a similar impression (everything interesting is closed) until I had to work with stuff where I didn't know the structure of the docs. Suddenly checking SO was quicker and had tons of relevant content.
But yes, it is annoying that there isn't an easy to find place to go for questions that require some discussion/debate and don't survive on SO.