Because the person who asked the question has accepted the first answer that looked decent enough and moved on.

Usually the most superficial, not that it's always a bad thing.

Oh, also on SO there's this kind of exchange:

Q: "I want to do X because of this and that - or because I simply fucking want to".

A: You should never do X, do Y or Z instead.

The "that's a XY problem" guys always seem to think they're the smartest in the room.