Do they lose their karma after deleting the post?

I personally think this is more of a culture thing than anything related to UI. So yes, moderation is very important to that, features/design/UI/UX to lesser extent. Memes on Reddit are mostly posted to subreddits dedicated to memes, you can actually just not subscribe to those. You can also use “home” feed instead of “popular”, “explore”, “all” so that you don’t get random irrelevant meme subreddits tossed into your feed. Personally, my biggest problem with Reddit is non-transparent moderation. And sometimes even automoderation. Things just get removed automatically for mysterious reasons, then you go ask why. Then question also gets removed silently without any explanations. That’s how Reddit moderation is nowadays. Lemmyworld also has some moderation issues and drama going on, but the whole platform is inherently decentralized and you’re free to pick any other instance with different admins and moderation choices. I already started using few more to see how it goes and to ultimately stick with what I like best.

The only tree structured texting thing from back then that I remember is mailing list conversations. If you remember any names of old forums like that, it would be interesting to research. Maybe there are still screenshots or archived pages of those.

I believe old style means linear threads and other oldschool UI choices, not just look/aesthetics. That one has tree comment structure similar to all redditlikes, which (I believe) is relatively a recent invention? Have you seen comment trees like this few decades ago?

Doomworld for new maps and mapsets for Doom 2 and Heretic.