Some people are idiots. They need everything spelled out for them. And a lot of crimes are the result of momentary circumstances. Most of them, in fact. If we can control those circumstances, we can stop a lot of crimes.
Most shootings are the result of guns being around people who are drunk, high, or enraged, or suicidal. If the guns weren't so available and close to hand and easy ti grab abd use in those momentary circumstances, many of those shootings wouldn't have happened. Stopping crime isn;t just a matter of making the act illegal. It's also a matter of making the combination of circumstances less likely to occur.