The little server mod this guy uses detects really noticable hacks like really really quick reaction time I.E aimbotting, if it sees you moving faster than everyone else (in TF2 you can't sprint so they'd have to do something special for Brink) it will kick in. Think about it this way if every server happened to have something like this hacking would be worthless, and maybe the hackers would end up thinking (I know a hacker thinking strange right <_< ) that since every time I try to hack I'm unable to do anything so maybe I'll try and play the game normally for once and stop being a stupid hacker.
An admin presence to ban the offender would be far more effective, on any decent server the painfully obvious hacks would be dealt with in a few minutes or seconds. I preferred the admin mod I worked with on Counter Strike which would point out to the admins on that "playername's view is upside down", an entirely automated systems seems like it would get in the way more than anything. Without the player knowing the system was automated also makes it so they are unaware of how they were actually "caught".
I am curious if PB or VAC has a list of unchangeable values (running speed, fire rate, etc..) that it would look at to see if someone is hacking. It is also important to remember that VAC works on a delayed banning system, so people saying that it hasn't done it's job because they see people are hacking need to look that up.
They would just make harder to detect hacks. Same concept with people who crack/pirate software.
And this.