I'm wondering how it's better.
If this description is accurate,
then everyone is waiting in line, including the kid who is too short to ride and the parent who is staying with the non-riding child.
With WDW's system, the child doesn't have to stand in line, and the parent waiting with the child can take the child somewhere else (another ride, a show, shopping, food, etc.), then come back later to use the child swap pass.