>Because you got a match against them? Because you have friends in their group? Or peers? In the game I played, the top players knew each other.

So it's avoidable. Just use another server which maybe you, or a neutral party controls. Doesn't matter if they know eachother. Having a match against them is not a factor, if you play vs. them you don't need to be in voice chat with your enemy to begin with, but maybe you have an example of a game where this is common.

>Actually, you got a good idea who does the DDoS; "supporters" (hooligans) of group X, who got your IP from admin of voice chat server of group X.

Then don't join group X. It's simple really. Or you gather evidence, seems simple enough if you just write timestamps.

You don't know beforehand who is going to DDoS you, or when. So, re: avoidable, a sensible solution is to just use a VPN for that specific purpose. Its easy to set up, cheap, and the added latency for voice chat is negligible.

Yes, but you know it afterwards. It's the overkill solution to a (probably) very small problem.

You don't have to route 0/0 through the VPN...

Then it's even more useless. Just use tethering.