A long time ago, I had a mstdn.social account and was trying to view a friend’s content on like mastodon.art. I couldn’t see his content via mstdn.social at all, but I could if I just went to mastodon.art. Mastodon.art was not in the list of servers mstdn.social did not federate with. I assumed this was a glitch.
Huh? If I manage to get my friends to sign up, we should all sign up on the same instance? Aka we should all use mastodon.social because since that’s the biggest instance, if I eventually meet someone who already has a mastodon account, they’re prob on mastodon.social.
You can do that, but once you get enough time in Mastodon, you’ll realize that what you’re saying is not that important. As @retiolus@lemmy.ml said, you may want to look for a better instance. Don’t worry if you don’t choose the right one, you can migrate your account (everything) any time.
You should not use mastodon.social “because it is the largest instance”. The Fediverse was not designed to “join the largest instance”. Instead, go to https://instances.social/ and find something that meets your criteria :)