this is my biggest pet peeve about mastodon. the UI leads you towards registering for no good reason. "Joining" a server should feel like an intentional decision without UI hints to get you there. UI for logged out users should help you navigate back to your home server, and take actions on the post there (reply, star, boost, etc)
I guess I'll take this opportunity to push my pet feature again. Fedi needs a URL protocol so that we can direct users back to their home server from any remote origin. The experience should be seamless so that non technical users can click a "see on my home server" link.