I wouldn't call it a good use of static typing, but I'd call it a good use of object-oriented programming.

This is one of the really key ideas behind OOP that tends to get overlooked. A constructor's job is to produce a semantically valid instance of a class. You do the validation during construction so that the rest of the codebase can safely assume that if it can get its hands on a Foo, it's a valid Foo.

Given that the compiler can't enforce that users only enter valid data at compile time, the next best thing is enforcing that when they do enter invalid data, the program won't produce an `Email` object from it, and thus all `Email` objects and their contents can be assumed to be valid.

I agree and for several reasons.

If you have onerous validation on the constructor, you will run into extremely obvious problems during testing. You just want a jungle, but you also need the ape and the banana.