That's one of the things, though. If you are in a dire situation, like companies nationalized during wartime, you can't work or function. Certain things like advertising your services are clearly out the window.

In WWII, some companies who were turned to serving the war machine continued to advertise the things they couldn't make or sell, anyway. When things came back those folks were on top of the world. If the big FAANG companies can ride out business cycles without acting like they've become vulnerable, they're likely to further cement their positions.