"Completely" is not the goal. Consoles aren't "completely" cheat free, either.
The goal is to make cheating hard enough that the average twelve year old can't easily do it or conspicuous enough that you can ban them when they do.
Because at that point most players will go from encountering multiple cheaters per game to encountering a cheater every many games, so the game looks like a mostly fair thing with a few outliers as opposed to an absolutely unplayable mess.
And since cheaters and hackers tend to flock to whatever is popular, particularly if they're monetizing their cheating in some form, the more popular the game the more of an interest they have in a secure-enough environment.
If you can't get that on PC they will focus on consoles. If you can't get that on Linux they will focus on Windows.