I get it. I understand supply and demand. The problem here is that STP has changed the "supply and demand" by, in essence, taking the "free market" out of it. The Supply no longer consists of ALL hotels/motels/inns/etc. in the greater Dallas area. The Supply is now "hotels that have agreed to our terms* and are on our list as acceptable". The Demand is also now steeper because ALL attendees are REQUIRED to stay in the Supply hotels (or present an exception form to be approved). What happens when you come up with that combination? Increased prices. So while, yes, prices would have no doubt increased year to year even if hotels were operating independently...by taking the free market out of it, the increase has been significantly steeper.
The losers here are the families. They can no longer negotiate directly with hotels or decide for themselves where they want to stay from a complete list of all accommodations. If they want to stay in a hotel in BFE that is "not on the list" to save money, they have to ask for "permission" by way of an exception. The inherent nature of having to file an exception gives someone (CH or NCA?) the ability to not grant your exception should they choose. Families are paying more in an artificial supply/demand environment.
I am certain NCA is able to negotiate better rates for the convention center based on the number or rooms they guarantee will be taken. Count NCA as a winner in STP.
The hotels? Well, I am sure they like the higher rates they are guaranteed by "willing to pay $50/bow" parents coming to town. I am also pretty sure that they have to boost their rates to accommodate some sort of "payment" (I am guessing flat rate or percentage) to CH. Because, face it, that is how CH is getting paid. CH is also a winner in STP. As far as the hotels --- Obviously some hotels do not consider NCA/HC a "winner" and have chosen to not partner despite their proximity to the Convention Center. Others, I would guess, despite the inconvenience of the noisy, rowdy cheer families, are no doubt winners in STP when you look at the rates they are able to charge for those days versus the rates the rest of the year.
So, I get what you are saying. I understand the "why" behind STP. But I would argue that those same # of hotel rooms in the area would be taken even without STP. Families have to stay somewhere. The problem is it is more difficult that way for NCA to show how many hotel rooms they are responsible for. So that proof comes at a price...and that price is borne by the families.