I think "shortage" means "scarcity," while "shortfall" means "deficit." Just because you have a shortage doesn't mean you have a shortfall whereby suppliers somehow failed. Of course, there have also been shortfalls....when a plant catches fire or production gets delayed due to power outages, that results in a shortfall.

Overall I'd say you're right. Capacity has so much inertia that it lags beyond the created demand. That isn't the fault of the foundries, it's just an artifact of unpredictable market behavior.