Because, they don't just make you invisible, they actually remove record of you being there. (I think this is so mobs don't attack you.)
Meaning you could grief and there would literally be no record of you doing it.
As such, the best option to stop anyone doing sneaky stuff, is to just remove the usage of the potions.
This is only my 50 Cent, so take it with a 2pac of Eminems.
(And yes, I do understand that price is Ludacris)