One problem with masks is that they are statically charged and that charge depletes pretty rapidly. So it's not as if you can create a bunch of stock for 'some unspecified time in the future', you'll have to continuously renew it at that level every couple of months. This is certainly going to raise eyebrows if there isn't a demand for a longer period of time and someone figures they can cut that cost without impacting safety. Which works. Right up until the next pandemic and then you're back where you were before. This sort of vigilance is very costly and it is hard to get everybody to agree on the appropriate level over time.