VAC is so not-good that there are not one but two popular third-party matchmaking services for Valves games whose main selling point is much stronger (read: more invasive) anti-cheat than VAC, and one of them even charges a subscription to play, which highly skilled players gladly pay to get away from the cheaters in high-rank VAC servers.

https://play.esea.net / https://www.faceit.com