Mastodon has made it easier to join up, no longer requires you to choose a server. Other features coming soon. https://blog.joinmastodon.org/2023/05/a-new-onboarding-experience-on-mastodon/
A new onboarding experience on Mastodon

Today we’re making signing up on Mastodon easier than ever before. We understand that deciding which Mastodon service provider to kick off your experience with can be confusing. We know this is a completely new concept for many people, since traditionally the platform and the service provider are one and the same. This choice is what makes Mastodon different from existing social networks, but it also presents a unique onboarding challenge. To make this step easier, we now have a default sign-up option that works with a server we operate. If you wish to leave or join a different server, you can do so at any time.

Mastodon Blog
I know there has been a lot of concern about funneling new folks into mastodon.social rather than having them choose a server. It feels like it flies in the face of decentralization. I get it. But… I think it’s a smart move. It offers an easy way in for folks so they can get a look at the platform, get a feel for it’s potential, and then, should they choose at a later date, move to server that better suits their needs or even spin up their own instance.