The idea is not that they should have had a stock for multiple years of demand. Rather, if you have a warehouse and are able to build a bit of stock, you can ramp up much faster.

The actual closings due to lockdown were only a couple of weeks in most industries. What really hurt imho was that orders were cancelled, production capability was scaled back, but demand came back faster than expected.

It makes sense why it would ease the initial shock from shutdowns, but how would it help with the cancelled orders and scaled back production? It seems like it would just stretch out the shock over a longer period of time. Would that actually stop the disruptions because it seems like they would eventually burn through all the inventory eventually because of that?

It takes two years to ramp up more fab capacity.