Cheaters are everywhere. Just one of the many reasons that these games are basically unplayable. Mix in skill based matchmaking, and good luck having any fun at all.
There's a cheap program you can buy on PC (there's many) that let you use a mouse+kb, but emulate a controller (so you get full aim assist), plus you can run things like no-recoil scripts. These things are used by people to customize controllers, so they aren't even designed as a cheat, but it gives people aim assist plus mouse.
There's also tons of blatant cheaters in Europe and other regions, to the point where people have to play on US servers. People are even advertising cheats in game.