I’ve been using Mastodon since Twitter was taken over by Musk, so I’m not a super long-term user, but I can give my perspective:
Platforms like kbin / lemmy are more like “topic” communities. Like people on kbin create “magazines” and on lemmy they are actually “communities”. From the user perspective, you can just look for these communities you are interested in and sign up to get updates from them.
Platforms like Mastodon are more like you and specific people you like to see content from. So you find people you like to hear from and you follow them to get their updates. They may post on subjects you aren’t interested in but oh well, that’s up to them.
Both formats can produce desirable, tight-knit communities, but they just use different structure. In my opinion, the kbin / lemmy style is more accessible in terms of finding people interested in a specific subject but feels less personal since you are just all there to talk about a specific subject. On Mastodon, when I find people posting content I like, I end up learning more about the random nonsense they are interested in. Like my feed there has a ton of moose pictures now because one person I followed likes to post pictures of moose. I don’t mind seeing them, but I never expected to see so many moose.
TLDR: Mastodon is about following people, kbin / lemmy are about following topics.
From what I’ve read, the troll farms mostly operate funded by Russia but are physically located outside of Russia. For example, Macedonia had quite a few.