Everytime someone invokes an argument how taking something away by law prevents some form of crime, my answer is a simple fact:

Criminals, by definition, don't follow the law.

Now, in some cases, that isn't a problem: Guns are an obvious example, because they take resources and knowledge to manufacture, and are physical objects that can be tracked. Taking these away by law works.

But encryption isn't a physical object or something that needs to be manufactured. It's math and algorithms. It can be copied infinitely. So, if the law takes that away, law abiding people will no longer have access to the benefits, while criminals will just ... well, as criminals by definition do, ignore the law, and still use encryption.