I just read this same question and answer on the moms panel. Below is a copy and paste of that. Personally, I think there should be some sort of fee or re-course for any and all no-shows.
C&P from disney site moms panel:
Hi again! We have the deluxe dining plan and I am currently making all of our dining reservations for our stay. If for some reason, we don't make it to a restaurant that we have a reservation to, does it get charged toward one of my dining credits? Thanks
If you're not going to make a reservation, the courteous thing to do is call Disney Dining at 407-WDW-DINE to cancel. This way they can release your slot to another guest. But even if you don't cancel, for the majority of dining experiences at WDW, there is no penalty if you miss your reservation. You will not be charged a dining plan credit if you do not show for your meal.
The only penalties assessed for restaurant no-shows are in cases where you needed to leave a credit card number to pay for or hold a reservation. These restaurants are Cinderella's Royal Table, Victoria & Alberts, California Grill, the dinner shows, and a few others. If you are a no-show for these meals, your credit card would be charged a fee, but you would still not lose any dining credits.