and if you get banned on one server, it might be possible to transfer all your posts to another given how they communicate with each other.

I've had an account there for some time, and mastodon is basically dead internet theory in action. Very few people interact with each other. I'd bet less than 20,000 active accounts across all the independent instances.

For a laugh you can look at all the twitter refugees introducing themselves. I checked like 50 of them, and 0 responses to any of them lol. https://mas.to/tags/introduction