Sorry but I believe what you read in incorrect. A hopper pass is very valuable! It allows you to hop to any and as many parks as you wish after 2:00PM as long as you have tapped into the park where you have your reservation. Some people have visited all 4 parks in the same day.
There is a disclosure that you may only hop to a park that has availability for hopping but to date there has never been an instance when any park was closed to park hopping. Please read post 1 of
this thread.