Its all to do with this "food abuse" debate. About how when you change the use of a free food it becomes easier to eat in larger quantities. An example is making cous cous cake. Made into a cake you would eat much more and be less satisfied by it than if you ate the cous cous as part of a meal. Same with the pizza, potato is quite a calorie dense food but it is free on sw because in its "normal" form it is very filling and not easy to eat much of. Drier and as the base of a pizza onto which you will put other toppings, cheese etc and probably serve it with another free food like sw chips, that ends up being a lot of calories on top of what you would have eaten without the potato pizza base.
The Warburton squares are a good alternative but as I do think use them I'm unsure of the syns. Try a search on here, I know I've seen them talked about lots! Xx
