[AstralStorm]

That's not exactly why it's steroids. If this was the main mechanism we'd use more effective immunosuppressants. As is, stronger immunosuppressants show worse survival rates. You want to keep some immune system activity to not get a secondary infection and fight the virus.

Corticosteroids also kickstart healing process (not really in COVID) and regrowth - you also race against tissue destruction. Most importantly they barely reduce scar formation. And they actually improve breathing via action on alveoli as well as reduce swelling.

The specific two to use are hydrocortisone and dexamethasone based on studies thus far, in critical patients - ones put on respirators. (Prednisolone could also work.)