m4d4m on Nostr: What are the +/- for the log-in? ...

What are the +/- for the log-in?

quoting
nevent1q…pc7p

#asknostr

Why should I log in to a relay serving someone's content? What is it good for?
(The relay could serve the note to anyone(?) unless it's a private relay and I should be a member - but I'm not, by default.)

What will this reveal about me to the relay?