> Come on, are you never wrong? We're all wrong sometimes.
Whatever you do you'll always be wrong sometimes. Answering Y is usually helpful, that's why people do it.
> I suggest that the 'race to be the first answer and get karma for it' is the motivator that drives people to do this on some platforms, rather than any actual desire to help / any actual competence in the question domain / actually knowing what they're talking about in many cases;
This is, if anything, even more true of people who answer the literal question asked while giving no thought as to what the questioner actually wants.
> a partial answer to X is never that time consuming.
Disagree. Often X really is something possible-but-difficult; you can give a "partial answer" in the sense of "I'll need a research team and five years", but that doesn't really help anyone.