Sometimes you just want to make sure it's not weird if you randomly show up idk.

Or they set the world to friends plus by accident.

Or you just don't like to show up uninvited in general and want to make sure it's okay to show up.

Or you want to send a quick message asking how laggy/overcrowded or calm it is before showing up.

Or maybe there's one slot left in a game world and you want to see if it's okay if you take it?

Lots of situations where this would be handy you know?