I'm not sure if you're aware, but only the first remote user needs to know the address. After that the content gets federated to the feeds of other instances automatically, including the new/hot pages where popular upvoted posts from the star trek instance can show up on the front page of other instances, allowing new people to discover, join the "sublemmy", and comment often without realizing it's hosted on a different server.

Based on my mastodon experience, it's a little more nuanced than that. You are on a server (not the star trek one). Someone on your server needs to follow stuff on that star trek server for it to show up on your server. So if your community is mostly about fishing and no one likes star trek but you, you'll never see it unless you go looking for it.

What? That sounds like a great way to pollute the tightly focused fishing server... There's got to be something more to it, right?

It seems you just got used to Reddit. I don't see how knowing the subreddit is (much) easier than knowing a website.

No? Why would you need to know the address? Also, that is not even true on reddit: you don't need to know whether it is /r/startrek or star_trek or trekkies or whatever; you just search, done.

Go check out join-lemmy.org, it's a lot more user friendly than you might think!