In this case it's not the theoretical maximum. It isn't available to regular apps because the OS and CPU don't allow it, for good reason - to conserve power. The reason benchmarking apps can do it is that Samsung added code to specifically detect them.

Your car spec analogy is a good one. If the car maker removed the seats and carpet as well as inessential engine components before testing, that would be the equivalent of what Samsung have done here.

It would also be fraud.