This, pseudonymous de-centralized discussion groups and forums, is what I would pick as the one thing I would like to bring back to the internet. There used to be a forum about everything, each one it's own community, most of which didn't require ties to a real-world identity.

I'm sure they exist, but they are really hard to find.

This was my immediate response. The number of forums available has plummeted. And as @maskros says, they are all in private Facebook groups now. Private because no-one wants their personal life trickling into their Facebook feed in case someone from work sees it.

The Internet is a dark forest. As soon as there is money to be made or power to be gained by exploiting something, the barbarian hordes will burn it to the ground unless it's behind towers and walls.

Came here to say forums. Niche areas of information which no social media platform can begin to compete with.

And what's frustrating is that you can't even search those facebook groups (AFAIK).

Big forums can cost a lot of money to run and managing the spam can be a mess these days. Not only that the boards that have enough proper tools to deal with the spam aren't free. Sure there are plugins for some forum software that fix a few things, but often you have to install 6 plugins and that still isnt enough, plus then you have to do updates and hope it doesnt break those un-official plugins.