Of course. Theory also allows us to exactly model the probability of such an attack succeeding. The difference between a system that is provably secure and a s

Of course. Theory also allows us to exactly model the probability of such an attack succeeding. The difference between a system that is provably secure and a system that is theoretically insecure but with no known practical attack is a pretty big difference. In the former case, your proof has to be wrong before you lose, in the latter, someone just has to think of something you didn't.