Just so you are clear, the reason people are saying that the higher water level will not allow for good skimming is not due to a mysterious "pool rule". It's just that if the water level is such that it is higher than the top of the inlet inlet area of the skimmer mouth, then floating debris, leaves, pollen, etc. will not be physically able to float into the skimmer to be sucked into the suction pipe at the bottom of it.
So pollen will accumulate on the surface and debris may have more time to become water logged and sink before being captured in the skimmer basket.
It's nothing serious, more of a housekeeping item that you don't want to have on a routine basis. It makes it harder to keep the surface of the water clean. The water is still being filtered regardless, just not the surface of it.
A little wordy but I was in an explanatory mood. If you already knew this just skip along!