I could be wrong but I'm pretty sure it is also illegal to steal someone's credit card and use it. If you have already done that, I don't think the idea of scribbling illegally is going to warn anyone off. Chip+PIN is objectively far more secure. People used debit cards with swipe+PIN for decades just fine and chip+PIN is used in many other countries without an issue. It is just silly to keep using signature and acting like it does absolutely anything at all.