It does sound like it’s by design, it’s really frustrating as a user though. I think people should at least be made aware of it and the instance admins get to choose how those comments are handled. That guy’s threads were great and should be shown.

This isn’t relevant to this particular case, but bad actors could control the narrative by using this as a technique. Just say something crazy, wrong, misinformation, etc., it gets challenged and spoken about clearly while other great stuff comes up, bad actor just deletes their comment. Who would bring this up with to see if it could at least be opted in to show replies to deleted comments.