Tom Fulp? The Newgrounds guy? Wow

This is a more general question, but how do corporations send cease and desist letters to randos on the internet who use copyrighted material in fan art that they don't sell? Like, wouldn't they need to literally dox you first in order to get an address to serve papers to?

And even in cases where people do sell the art, it's usually commissioned stuff, especially when it comes to adult content, right? I can't see how Nintendo would extract evidence from between the artist and patron in order to make an accusation.

Tomodachi Life sequel w/gayness settings pls