Isn't that highly subjective, however? Two people show up to the hospital feeling equally lousy, both test positive for Omicron. First guy says he's vaxxed and boosted, doc suggests he's fully protected, this is the worst of it, go home and rest up (which is exactly what a doctor told my father). Second guy says nope, I'm unvaxxed. Doc is probably going to admit this guy overnight for observation.
Multiply by tens of thousands, and you can project the effects on hospitalization stats, which aren't necessarily tied to the degree of illness.