People hoarding aren't trying to create artificial scarcity. They are buying because they anticipate scarcity, and want to either (i) be prepared, or (ii) profit from resale.
Hoarding has caused shortages which, in turn, justify the original hoarding. This is a sad situation, but capping prices isn't a solution. If anything, I would expect higher prices would discourage hoarding, resulting in a more even allocation of TP/whatever between people.