True, and really there's always some kind of super-high friction loophole in computing. For these types of loopholes to have an impact though a) people have to know about them, b) people have to be able to do them, and c) they have to be easy to do.

TestFlight is as easy as getting an email, downloading the testflight app, and downloading the app you need. Its a trivial amount of steps, which makes it a powerful loophole.