Perhaps because increasing PO2 is not a particularly effective way of increasing oxygen carrying capacity? Once you get past 95ish your not going to get a whole lot out of the system.Also, this. A very salty, incredibly intelligent street medic once told me that it doesn't matter if they're compensating; if they're fighting to compensate and hold that 96, they won't be compensating for long.
"Salty" and "knowledgable" are, sadly, often two very different things.