Essentially secure boot is supposed to validate that only properly signed drivers are loaded on system startup. That allows you to block malicious/cheat drivers from being loaded because a signed AV/anticheat driver was loaded before and now it can properly control drivers that are being loaded after it.

Without it you are risking that the malicious driver will be loaded first and then make itself invisible to the later drivers.

Of course there are ways to bypass this too, but it adds a whole other layer of complexity.

Tldr

Secure boot is there so drivers loaded at boot time can trust that nothing was tampered with before they were loaded.