Ok so I’m just curious, not really planning on using it but why is CEMU banned? Does it give some sort of advantage or what???

I don’t know anything super detailed about CEMU but more than likely it speeds up loading and/or performs better than an actual console. This tends to be the case with most emulators for consoles PS2 and later.

It's also harder to prove that there aren't cheats on an emulated run.