But you don't have to actually know them. If they posted their Tox ID on 4chan, which happens all the time, and they accept my friend request, I would have their IP address, correct?
How else would you connect to them in decentralized fashion? Your IP address isn't really useful information anyway.
Note that being friends in this context means the users have added each other.
You could implement onion routing. But yes, you are right the IP address is usually a useless piece of information.
True, but for VOIP that is guaranteed to be terribly slow.
Ip addresses change. Sometimes they don't even work for P2P. Without ICE or something its hard to even know your public IP address programmatically. So often some kind of proxy or server is necessary for most people. True decentralized connections are a sketchy proposition.