Wikipedia can also be “moderated” by anyone. If I see spam or incorrect info on Wikipedia, I can edit it myself. Maybe reword things, add references, etc. On social media (FB/IG/etc), I don’t have that choice. My only option is to report it and hope the moderators don’t say “this [x] doesn’t violate our community standards” on a clearly spam/scam account/comment/post.

I’ve reported so much garbage on social media only to be told it’s not a scam or whatever, I’ve practically given up trying.

Yes. Perhaps that's a clue?

FB's groups are terribly designed if you want to have a conversation and keep a collection of useful information.

They're cleverly designed to keep people scrolling forever on a content treadmill - in no way the same as optimising them for usefulness.