Technically speaking, using camo skins isn’t currently against the rules in the skin section of the rules.
I argue that these skins provide an unfair advantage to the computer and mobile players who use camo skins to hide, instead of playing the game in a legitimate way.
This is mainly an issue in Ghost Invasion, where the dark maps make successful camoflauging much more common. Having to take time to find these players is just frustrating. Usually it’s a game that the ghosts have basically won that is now being stalled because somebody decided to be cheeky and use a camo skin. This could become an issue in other games like murder mystery as well, but probably to less success as described in my first reason.