Webray, you say this with some authority... are you a CM?
I would have to respectfully disagree with you. I consider a discount something you get with a coupon, a membership or the like. For instance, I could not combine my 10% AP discount to this meal in addition to the 20% DDE discount. On the other hand, ordering something from the menu - such as a 3 course lunch special - is not a discount. It is a full meal pulled together by the chef at an attractive price.
At the end of the day, my primary beef is not that I couldn't get the DDE discount, but rather that it I didn't know I wasn't going to get it. If they want to exclude lunch or dinner specials from the program, they need to say "excluding lunch and dinner specials"! I would never have guessed that the discount would not be offered on our order, and had I known I would have chosen something else from the menu, or possibly not even dined there at all.