I can appreciate the RVPR position, they don't want to get involved in personalities and such. Many times a sentence that starts with "The CG owner was a jerk..." could be finished with "...because he yelled at us for dumping gray water at the site." You could see that coming just from who posts what here on this forum LOL.
HOWEVER, I would consider Reservation Policy to be a physical attribute of the CG just like site width and power quality. If the reservation was not guaranteed because no deposit was taken, then the park should have advised as such when the reservation was made. Then you as the guest can make that decision whether to keep that reservation or make alternate plans.
There is a slight difference in perception between "The owner didn't honor my reservation" and "Be advised that this CGs policy does not provide for guaranteed reservations." You could probably take that last sentence and add something about the park being clean, quiet and convenient and get that review posted.
After a career spent in the credit card business, I can tell you that this policy is the exception not the rule. Back in the 70's it was fairly common to arrive at your hotel late at night and find them sold out...because the no show rate at hotels was very high. People would never take the time to cancel reservations if they couldn't arrive or plans changed. So the hotel is faced with the choice of either selling the room to the guy standing at the desk with cash in his hand or holding it for a guy that may or may not show up.
We solved that in the 80's with Advance Deposit using a credit card...the hotel promises that they will hold that room for you no matter what and in exchange you agree to pay for that first night whether you show up or not.
This has worked so well that the policy is universal at hotels and inns, and common in CGs, boarding kennels, almost anywhere that takes reservations (except restaurants). So to run into an establishment where reservations are NOT guaranteed is both unusual and worth noting as a review point, and is just as valid as part of a physical description as how level or wooded it was.
Nobody wants to travel a long distance only to find there is no place to stay...if the CG wants to maintain this old-fashioned "not guaranteed" policy, then they need to inform folks as such when the reservation is made.