Two Ground Wires in One Terminal - Within a Light Fixture

I would be very interested to learn how this construction would not be acceptable in any environment.

The ground bond between the conductors depends only on the crimp on each conductor, and the tightness of the nut on the threaded stud.

The ground stud and mounting plate could be an insulator and it would still work.

If you had multiple studs, you introduce more failure points in the system.

Yes, that is called "grounding redundancy", minimizing any ground loops.