Academia - Should I delete a bad answer even though I don't understand why it is bad?

I think that your answer is not bad but a bit naive, as coming from someone who hasn't really seen how much time and energy a crackpot is able to drain if one tries to be understanding. During the newsgroup era there were crackpots who went on for years with the same arguments. But I also think that your answer doesn't deserve so many downvotes, and there's no need to delete it.

I think the main reason your answer is rather massively downvoted is that in addition to the naïveté you're a bit too positive about people academics call 'cranks' and also that your first phrase sounds like an accusation and immediately triggers an emotional response (retracting the accusation doesn't retract the emotions I'm afraid).

So it's mostly the severe cultural mismatch (with academic culture) and lack of neutral tone in the answer that gives the downvotes, I presume. I can edit the post to be more neutral and more 'culturally fitting' if you'd ask. (I propose this here instead of editing myself, as this would be (at least likely perceived by reviewers as) conflicting with 'original intent')

Although actually, that likely won't remove the downvotes. You could consider deleting your answer and starting over with a new one, rewriting it from scratch with what you learned here and take care to be neutral on this slightly sensitive issue where your view can be easily seen to be controversial. If you do that, I don't think you'll reach as much downvotes again.