I think a "normal" user isn't likely to hear about PeerTube and immediately think "how can I join this?" Rather, someone might send them a link to a cool video

I think a "normal" user isn't likely to hear about PeerTube and immediately think "how can I join this?" Rather, someone might send them a link to a cool video like https://video.blender.org/videos/watch/8533ea43-4271-4a57-9694-e9d0b35e1aa1 https://video.blender.org/videos/watch/8533ea43-4271-4a57-96... and if they like it, they look at some of the other videos on the same instance. So discovering an instance you like is not that much of a problem if you're not starting from the central project website. Of course the instance that has the videos you like may not allow just anyone to create an account (e.g. video.blender.org doesn't) at which point it does get pretty confusing, because you need to move to some random other instance for no obvious reason. (Of course the reason is decentralization, but "normal" users don't care about that as an end in itself.)