Maybe I'm a little dense too. Or maybe 4x4van just needs a nap. Based on 4x4van's comments in other threads, it seems to me that he/she is a little cranky.
As far as 50a sites go, I'd be upset if I pulled up to a park and there wasn't any room for me because tenters took all the 50a sites. If all the tent sites were full and they just took what's left, then there wouldn't be anything for me to complain about. But if they took the 50a sites instead of tent sites, then I'd be upset with them and mad at the park.
I pull a triple axle fifth wheel and my selection of spaces is limited. While a tenter could camp just about anywhere, I can only park in the long spaces (typically 50a). So if they take the 50a spaces, then I'm probably out of luck. I would never dream of taking their spaces and edging them out when we could easily all have our own spaces where they get theirs and I get mine. That's an "AND", not an "OR", which equates to an "US" and not a "ME".