The distinction is that Mastodon doesn't have to grow, and Bluesky does. There's an extent to which Bluesky is viable because its venture-funded owner pays for the infrastructure it operates on (Mastodon communities generally have to stand on their own two feet). If there's no path for Bluesky to grow into a viable business on its current financial runway, the funding for the infrastructure will end.

I'd love to see similar plots after you remove the primary servers in each! To give you a rough idea: 78% of the people I follow on Mastodon are not on the primary instance, and over 80% of my followers are not either.

> Anecdotally, Bluesky feels more lively for me because that seem to be the default destination for Twitter refugees.

It likely is the default of Twitter refugees, but as a Mastodon user none of this is relevant to me! I don't care how many more users a network has, as long as the one I'm on has a healthy number. Very few of the people I follow are likely to leave Mastodon.

Mastodon isn't trying to compete anyway, it's not a Product(tm) driven by desire for profits, so the people who use it don't care if it "wins" or becomes more popular than whatever other platform. We're all just hanging out socializing and stuff, sharing neat things and discussing things like communities do. It's not easy to accurately estimate active Mastodon/Fediverse users, but then again, I'm not sure anyone really cares either way? lol

I am on several socials, personally I like the crowd on Mastodon the best but they all have their charms. I mean friends, furs, family, people I take street photos of, local radio personalities and people who look up to my character can be found in many places.