As more of the Store Islands came up on the map, those islands were moving in a particular direction even though the instance that they were in was just one big open ocean. Everyone in those Store Islands was currently restricted from moving between Islands but to most of them, it was not a concern as the Pandarens were frantic in their purchases.
Even though each and every one of them could use an on-site service menu, everyone knew that buying from the Supplies store had the most discounts available. Jin predicted previously that people would swarm the store and had already expanded the store by having peddlers and street vendors selling the very same thing as well.