Yup - that is the idea. Restaurants that use this are generally oversubscribed and relatively small so every no-show was a dramatic hit on their bottom line. I think I read that some restaurants saw something like a 10 to 15% no show rate which not only hits their profits but makes it harder for those that want to go.
You pay for the meal up front, and in some (Alinea) the price of the meal varies based on the time of the booking - so cheaper at the less popular times. If you can’t make it then they often have secondary markets to “resell” the tickets. So its just like theatre or concert tickets.
I believe that part of the reason restaurants have had to go down this route is that credit card companies have some rules in some countries that don’t allow for no-show penalties (the US for example ?). In countries that do allow no-show penalties its quite common for restaurants to take the credit card details on booking and charge a fee if you cancel less than 48 hours in advance or don’t show up.