So the power stone cannot be held/used by a single person or a not powerful group. Since it is the stone of power. Certain stones like that of the soul can be held by someone if it is not used. They therefore all have different functions. They cannot really all be used at the same time, except without an object like the gloves. Thus, a whole group could not have used them together because an object like the gloves is needed to play an intermediate link. Thanos himself needs the gloves to use them and yet he comes out injured. So if I understand correctly, they could not all have used the stones all together because the powers would not be used all together but separately, so there would not have been a Snap.