You are correct. COVID is different from other respiratory illness I'm aware of (not a doctor) in that when it gets serious that way it interferes with oxygen intake but not getting rid of CO2. Which drives the breathing reflex so you can get "happy hypoxia," where oxygen blood levels get dangerously, perhaps lethally low and the patient doesn't realize it, especially since hypoxia is insidious.

Another difference perhaps is that the SOP treatment, US, U.K., don't know where else is to give anyone bad off enough to require supplemental oxygen a steroid to suppress the innate immune system.