Please everybody, please post your "obscure" questions to Stack Overflow. Yes, it's unlikely that you'll get a good answer in any sort of useful timeframe for many of the reasons the OP lists.
Sometimes you do get a good answer quickly, saving you hours of frustrating searching.
But most times you will have to spend hours figuring it out yourself or you'll end up giving up. Answering your own question won't get you a lot of points but it will probably get you a few over time. More importantly, because of SO's high google rank, you've made your answer easy to find for the next few people who have the same quesiton.
The core problem lies deeper than the reasons OP listed, though: Complex problems require tradeoffs, and tradeoffs require discussion. Stack overflows format is 100% incompatible with discussion. Thus, Stack overflow is largely incompatible with complex problems.
Incompatible by fiat, not by any technical reason. There is no reason the comment system couldn't be expanded into a more extended/threaded system to allow precisely that.
That and the "not a good fit" close reason is the primary thing wrong with SE.
You may also get attempts at answers which don't answer the question, and then people whining at you to accept one when none of them are actually adequate. A small price to pay, admittedly.
Sometimes you do get a good answer quickly, saving you hours of frustrating searching.
But most times you will have to spend hours figuring it out yourself or you'll end up giving up. Answering your own question won't get you a lot of points but it will probably get you a few over time. More importantly, because of SO's high google rank, you've made your answer easy to find for the next few people who have the same quesiton.