On the RV suitable to site size issue I have come across a few CGs which follow this policy. It is for their own good. A class B may be able to get into a site suitable for as class A moho but the class A moho is not going to fit into a site suitable for a Class B.
If tenters, small trailers, small class Cs have taken up all of the large sites the CG loses. The larger rigs take their money elsewhere. The CG most likely has empty sites that the smaller rigs could have used.
The assumption is that all sites are more or less equal as far as views & access to CG amenities go.
It is called having consideration for others. That RVer with the large rig could be a fulltimer, or a multi month traveler who does not know every park & does not make reservations because he does not know where he will be from day to day not a weekend camper who goes to the same park every weekend & knows every site well.
Only recently we had to move in a Washington SP because there was no tag on the post to indicate that it was reserved. It was one of only a few sites capable of taking our size in the park. No special views. Not close to the restroom. Nothing special about it at all except the size of it. Turns out the rig that reserved it was a tiny Scamp TT which could have easily gotten into any one of a number sites in the park.
Had we not been able to shoehorn ourselves into a site & let 10' of our length hang out behind the site, the CG would have lost our 6 night stay. The Scamp only stayed 2 nights.