> Cross contamination is not a concern when someone is dying here and now and likely has the same disease as the guy next to him who is also dying

If COVID evolves into multiple strains, then there is a real risk of cross-infection that would make the immune system forced to work harder? Moreover, a lot of the pneumonia deaths are not due to covid itself but rather due to opportunistic infections (often bacterial) that end up causing the pneumonia that causes death. Letting two COVID patients share a ventilator could mean that now one is exposed to a novel bacteria in the other that causes them to develop pneumonia.