Right, always answer the question, even if you don't think the answer will be helpful: you might be wrong, and if you're not then providing the answer is likely to be the quickest way for the asker to find out that they didn't need to know.

But also: don't ask "why do you X" if someone hasn't said they "X". On this occasion I didn't particularly want to enable both A and B, I just noticed the problem when I briefly did.