There are plenty of RVers out there that don't require the 'best' parks with amenities. To them, the park is mainly a sleeping/resting place. They do their activities outside the park.
There are also many, many RVers who don't want to pay the high fees that many parks charge just because they may be in a particular area. People want options and they can get it in many ways. This is where Passport America comes into play. It works very well for many RVers.
There are other good options, especially if you're a senior and use the national senior pass. This give you a site for 1/2 price. We could either stay at a forest campground at a minimal price a few miles from West Yellowstone or in West Yellowstone at their pricey RV parks. We'd have a private site with the Madison River running in front of us. It's a no-brainer for us. Many times we've stayed in national, national forest or Corp of Engineer parks for $6 and up. We don't care about not having hookups. RVs are self-contained for a reason. We want a nice large scenic site. There are also county and city campgrounds that are awesome.
Some folks want hookups but don't want the other frills. That's where something like Passport America comes in.
Bottom line....not everyone wants or needs an expensive park to stay and for those people, that is the market for Passport America. They've been in business 24 years so it must be working. I don't understand why folks have to cut down others because of the way they choose to RV/camp. Everyone is different. One way does not work for all.