That wouldn't particularly change under the system that I'm proposing, idt. (on the back of a fag packet admittedly)- legal protection and the payments mechanism aren't intrinsically linked - most of the consumer protection with cc came long after the cards had been introduced. If you had an overall limit then the thief couldn't go over that, and a similar mechanism could/would exist - it'd probably be a product differentiation, in fact.

My understanding is that the protections that come with credit cards are a natural result of contract law. When you buy something with a credit card Visa pays for it and you agree to pay them back. When someone buys something with your stolen card Visa pays for it but you did not agree to pay them back, so there is no contract and no debt. Someone stole Visa's money, not yours.