It's not a server turning you in, it's the PB program that you installed on your own computer...along with the server-side app. If it finds material that constitutes the global ban, then you're gone. It's not some kid on the other end saying "global ban that player".
By buying the games, you agree to rules. Rules that include not circumventing it's copy protection, stealing or passing out keys, or altering it's program in any state. PB is not the one to blame, it's just the COP enforcing the rules the end user agreed to. If you do these and then decide to come out in public to play me, then get caught...you're banned. I'm very happy with that aspect of PB. What I'm not happy about is the random errors, but I'll live with that as long as cheaters and theifs are finally cracked down on.
And a cheater, is a cheater, is a cheater. There's nothing saying that if you get caught cheating in one game, then you won't go cheat on another game. I also respect this practice as it's a "zero tolerance" one. PB just up and says, "nope. You cheated here, you won't fool me again. Global Ban"
The only downfall I could possibly see is the very rare chance that some user with a false CD key has one identical as mine and gets ME banned. But I've yet to hear one of those stories yet.
But in all, Ignorance isn't bliss here. You get caught on a PB-loaded game, then you're out of that ever growing family of games. And, for once, people may actually read the EULA instead of just checking "I agree" and moving on.