If you search the net, you will find plenty of sites claiming it doesn't. However, as a personal experience, when I consume chocolate, I break out with pimples. I do not know if it's the chemicals that manufacturing companies include with the chocolate, or if it's something else that my body just doesn't like about the chocolate. For me, as far as I'm concerned, eating chocolate DOES cause pimples.
Think of it this way: If I'm an indigenous tribal person living deep in the Amazon rainforests all my life and I've never seen a snowstorm before, I'd say snowstorms are a myth, much like people whose skin don't respond negatively to "chocolate" say that "chocolate" doesn't cause pimples.
Much like a person may be able to eat shellfish, someone else may be allergic to shellfish. An ignorant person who isn't allergic to shellfish may come to the conclusion that it's a myth that humans can die from eating shellfish due to allergies. That is the wrong conclusion because some people can and do die from eating shellfish because they are allergic to shellfish! For you, it may be different. My reality is not your's. For me, I know eating "processed chocolate" causes pimples.