Imagine all paying resort guests bringing one or two extra people how crowded and unfair it would be to the paying resort guests
But you are a paying resort guest too, so I don't see it as 'unfair'. I totally get why people can't pool hop to different resorts, that I can see as unfair. You aren't paying to stay at that resort, you shouldn't have access to that pool. It would be like staying at the Hilton and then walking over to a Marriot to swim and saying "hey I am staying over at the Hilton, why not ?"
But if you are paying to stay at a resort, and thus have access to the pool, why not be able to have guests at your resort, including in the pool. Should you not be allowed to have people come visit your room ? because they will have to walk along the pathways and hallways of the resort, and make those more crowded too ?
In fact you don't pay any more for a room with children vs a room without children in it. If its my wife and I at POR for 12 nights in May, its 2700, if we bring 2 more people, its still 2700. So its not like you pay for extra people, and someone who brings guest gets them for free.
** Although, you do pay extra for extra adults I think, which is weird.