Absolutely correct. True story, though I'm going to leave out the name of the SIG to guard our favorite head chef....
Once, I suggested to Chef P. that a really good addition to the menu would be something not available at any other WDW restaurant... an Abalone Steak. These are VERY expensive now (though they were cheap in CA in the '60's before everything got fished out). We can debate as to whether or not anyone but me likes something like this, but Chef P. thought it sounded great - unfortunately, he simply could NOT put something like that on the menu. I asked "why not just charge appropriately for it?" Direct answer: "Because if it's on the menu at all, we would be KILLED by the DDP."
I think Dave's suggestion is excellent - it would remove the "DDP ceiling" that the Chefs at the Signatures face on a regular basis, allow them to offer higher end dishes, and still offer DDP dining. Right now, they have two choices: DDP & limited menue, or go the V&A route (don't accept the DDP at all).