Edit: and what do you know, 16 minutes after cross-posting this to !piefed_meta@piefed.social, Rimu agrees, changes the code, and deploys onto piefed.social to retain deleted posts. PieFed really is something!! (announcement post)
If a question is deleted for seemingly no reason on asklemmy, after people have provided quality answers and the comment field is reasonably healthy, I usually issue a ban. It's technically not against the rules, but it is very much against the spirit of the board, and it's not fair towards the ones who took their time to answer.