Considering the complete lack of attention TF2 gets from valve I wouldn't consider it a fair reflection of VAC's effectiveness. It had been infested for ages before a media outcry about the bigoted chat spam finally spurred valve into action, yet all they did was ban f2p accounts from using chat.
I don't play CS that much but afaik aimbots are there as well. I know that it has manual reports/user review systems so I imagine VAC is not effective as an automated tool
Counter-Strike has a bunch of anti-cheat systems, but they solve different problems (VAC, Overwatch, Prime Matchmaking, and VACNet). These systems all work together and I'd say it's pretty effective. TF2 could do with the same.
But my original point is that you don't need Kernel based spyware to do anti-cheat.
