The reason people ask for foamboard is it more widely known than PVC board, we have a rack with different materials that people can hold / feel before they make a purchase.
So when someone asks for foamboard we hand them a piece then a piece of the PVC board and 99% of the time they got with the PVC board once they see the durability difference.
with that it is always a good idea to have a board of it on hand at there are some people who will take nothing else