Link for anyone curious:
I'd suggest Mastodon to anyone looking for a new social media platform to join, but I can't suggest Lemmy/KBIN as they don't have legitimate blocking in place, as theirs is simply the same bullshit Reddit like "masking" where you can no longer see who you blocked, but they can still see, and reply to whatever it is you post, which of course is rife from abuse from the people you want to distance yourself the most from. Until there's legitimate, you no longer exist, blocking on Lemmy/KBIN I would suggest anyone else use them. (to say nothing of all the errors in KBIN from notifications, to blocking, to posting, to seeing comments, the list stretches endlessly)
My problem with mastodon is the same one I have with Twitter. It’s very easy to get up and running. You can get a feed filled with nonsense to read but if you’re actually interested in any topic, it’s really hard to get a feed that matches your interest. 
Yeah, Mastodon is great for following people, but not wonderful for topics. I hope that Lemmy can mature to the point where it has a greater diversity of communities.
Mastodon now lets you follow topics aka hashtags
Next step - Lemmy stats.
I knew mastadon was the largest, but I didn't realize how much larger it is. Mastadon is 78% of the fediverse users, while lemmy is third place at 3.3%. Misskey is second place with roughly double lemmy's users. Looks like it's a jp only thing.
I think most of the stats are deceiving. In my opinion, most of the actual activity or users read, and comment happens on Lemmy, as opposed to mastodon where you mostly just have observers. 
