Not necessarily.

Usually when micro-transactions are present everything is validated server side, Leading to always online games like diablo 3+.

From my understanding kernel level anticheat is to detect things like aimbot, wallhack etc.

Off the top of my head, Genshin Impact is a mostly single-player game with some multiplayer functionality. It uses kernel level anti-cheat to make sure that microtransactions are protected. This driver had a known vulnerability that did not get patched for years and was used by malicious actors: https://www.bleepingcomputer.com/news/security/hackers-abuse...

Street Fight 5 did the same thing; it was possible to unlock characters for local play using a trainer. They patched in a rootkit with known vulnerabilities in an attempt to prevent that.

I don't really think that's true. the content is usually in assets and just behind some flag that gets activated via some callout to a store, but there's not active anti-cheat software making sure that you "actually bought the content" in general()

() technically a lot of games have anti-piracy measures that are somewhat active, but they're rarely of the "phone home" variety