Except that's not how it is used. For instance one person who was arrested, tried and convicted like this operated a UK based betting company that US nationals used to bet.

Instead of going after the betters a secret indictment was passed which was then used to arrest an exec of the company because of course American laws apply to any business done over the internet...

https://en.wikipedia.org/wiki/David_Carruthers

The general view of people in that industry was that it is A-Ok for Americans to gamble, but not ok for them to gamble abroad.