I think this is due in part to the gamification in stack overflow. Often Y is a very detailed question that few people know the answer to. But X is a more gener

I think this is due in part to the gamification in stack overflow. Often Y is a very detailed question that few people know the answer to. But X is a more general problem that anyone knows some answer to. So you answer the question you know how to answer, even if it wasn't asked. However, at least in the case of stackoverflow, you're getting advice for free, even if it's occasionally unhelpful. You aren't entitled to an answer.