@wavesculptor

"you'll only see # mentions in your home timeline from instances that you or those you follow actually /already/ follow actual accounts on"

Just to be clear, you can see posts from any account followed by anyone on your server. So if one person follows a remote account, everyone on their server will also be able to see that account in searches etc.

The reason it doesn't show everyone on every server is to keep running costs low enough for anyone to start their own server.