That would be because many arts share techniques, and people claim that someone charging forward throwing chain punches is doing Wing Chun or something when in fact they're just chain punching. Have a guy in the octagon doing this;
And we'd have an entirely different ball game.
Except Jow Ga and traditional CMA in general looks nothing like Muay Thai. Thus there's no way for people to confuse it with the standard kickboxing striking style you see in MMA. Additionally there would be no confusion with Bjj either, since Chinese ground fighting is rare to nonexistent because of the belief by CMA exponents that they can shrug off the takedown.