But that's not a good way of doing it. A one-word reply rarely makes clear what needs more explanation, or even that that's what you're after.
On the other hand, a low-effort, drive-by unsupported claim doesn't necessarily deserve great effort and eloquence in a response. Maybe we should be better than them, but we also all have limited energy.
Some of us are kind of dense. I did not reply to the "Why not?" reply because I could not decide if it was intentionally a question about one of the things I said, or if it was a tongue-in-cheek example of someone who only uses three words or less.
Pretend I am dense, and give me a better idea of what I didn't explain well enough, and I'm happy to oblige. Everything I say makes sense in my head but I don't always communicate it effectively.
On the other hand, a low-effort, drive-by unsupported claim doesn't necessarily deserve great effort and eloquence in a response. Maybe we should be better than them, but we also all have limited energy.