nor can a 4 year old sit through an entire meal that is an hour and a half long, regardless of if it starts at 5 or at 8.
So based on your reasoning, should it not available for those who "had the choice" and selected late seating. Or for those with 10 year old kids and not 6? Nope, it is available to everyone in late seating.
I'm not saying that there isn't a need for it in late seating. And I agree that the need might be greater. But that doesn't mean there isn't a need for it at main seating, and it doesn't make it ok for them to only offer it to those in late seating.
This is Disney. A good service is a good service and should be there for all to enjoy.
Do you really think it is ok for them not to offer this for main seating? Can you honestly say that people in main seating don't have a need for it or wouldn't use it if the choice was given to them?