Absolutely untrue for Steam. A game on Steam might require kernel anti-cheat, but you're obviously not obligated to buy or play those games just by installing Steam.

And as mentioned, I don't put much trust in kernel anti-cheats in general, which is a big reason why I primarily play single player games. Which is why I'm extremely annoyed that a single player game that I might otherwise play comes with a kernel-level always-online DRM, all to protect the sanctity of predatory lootbox gambling monetization.