Remember when you were a little kid? If you formed a "club", it wasn't any fun if every kid in the neighborhood was in it.
Remember Stewart Oleson, that had an Rving series on TV a while back? I remember him featuring a Class 'A' only park in the southwest where folks purchased their spot. Each spot came with a small building that had beds, storage, a patio and a real kitchen. Probably attractive to full timers that wanted to stop moving for a little while.
I remember driving by a couple of RV Parks on Hilton Head Island that may not have been exclusively Class A, but when I drove by, it looked like it and they were priced like they were.