What's wrong with Stack Overflow
Stack Overflow isn't a community of developers.
The designers set out to gamify it and they succeeded. It is a long running game, and unsurprisingly it is dominated by experienced players of that game, who think - with some justification - that it exists to support their game play. As a result, the ostensible purpose as repository of knowledge is subordinate to the actual purpose (the game) and anything that "is not a good fit for Stack Overflow" is summarily rejected. This isn't just the players being jerks, it's designed into the game, baked into the rules.
So if it's not a community of developers, what is it? A community of gamers, playing a game that involves information that is incidentally useful to developers. The creators wanted to build engagement and comunity. In this they were very successful. But it's the wrong community.
Well... that's a matter of opinion. For players of the game, it's the right community. If you're a developer looking for a mutual assistance community of developers, then it's a great big lie, pretending to be there to help you but telling you to fsck off the moment you don't play their game. That would be okay if their whole game didn't depend on exploiting your need for answers.
What to do? That's easy - get your own community going. Which is really hard with Stack Overflow stealing attention and priority in search results.