how not having Punkbuster / a GUID all of a sudden means that "you cannot ban anybody" and "you can't protect your server from meany h@xx0rs and ch3aturz!!" (according to that thread that's been linked).
I wonder how we all managed to do exactly that BEFORE there was punkbuster.
You sound like a crotchety old man. "Back in my day, we banned people by IP, and that's the way we liked it!" Sure, it's easy to ban people without some kind of GUID system (doesn't have to be punkbuster). As an example,
A rampant cheater joins and ruins the game for everyone. Server admin enters console command to ban the IP.
Cheater rejoins with a new IP. The match is ruined until admin enters console command to ban the IP.
Cheater rejoins with a new IP. The match is ruined until admin enters console command to ban the IP.
Cheater rejoins with a new IP...
And so on. You can replace "Cheater" with "TKer" for the same effect. Banning ranges of IP addresses ends up banning people you may not want to. A good solution is to use a GUID system, so you can ban a person regardless of the person's player name or IP address.
Yeah, there have always been other ways to control access to a server, but why take a step backwards?