I suppose someone would be happy, but I think that a specific rule would be a big mistake. For example, what if I place a receptacle 300 feet away from the service for a 120 volt, 0.27 amps (32 watt) chlorinator, will we be testing the voltage drop at 12 or 16 amps? Or maybe as it is a single receptacle, 1.5 amps (180 watts)?
This is just as silly as 2% for feeders and 3% max for branch circuits when I have situations where it makes far more economic sense to go some other ratio to meet 5% max overall. This is one reason why these should remain fine print notes or general guidelines.
When we are to specific we through out common sense. For example the rule requiring when circuit conductors are upsized for voltage drop, a corresponding upsize of the equipment ground must be applied throws out an engineered system that sizes the equipment ground properly.