If you go back to my example, you’ll notice there is a UserUniqueValidator, which is meant to check for existence of a user.

Oops, right, I just glanced over the code and obviously missed the text and code had different class names. Another smell in my opinion, choosing class names that only differ in the middle. Easily missed and confusion caused.

I don't think our opinions are too far off though. You're just scaling the validation logic to realistic levels and I warn that in practice coders extrapolate too quickly and too often, which results in too much generic code which is naturally harder to understand and maintain than specific code.