Is that true? I thought it was the opposite of that... if you buy (resale) at one of the old properties, you can't use your points at Riviera, not the other way around.
Regardless, that argument only works if people actually pay the cash price. People make the same argument about the dining plan, how it props up artificially high prices at restaurants. In theory that's true, but there aren't enough dining plan guests (or DVC members) to support these things on their own if nobody is actually willing to pay the cash price.
I guess, if you place Skyliner access on par with monorail access. I don't expect people will.