It is that simple.
90% of the people in the hospitals are unvaccinated still.
Cut the unvaccinated fraction of the population down by 1/3 and you cut the hospitalization rate for the next wave by roughly 1/3.
Instead people are doing T-cells/B-cells and affinity maturation the hard slow way.
If we had a 100% vaccination rate we'd be done.
Don't know why everyone so desperately needs to look for counterintuitive ways to approach the very simple problem that when there's a global pandemic you mitigate it with vaccination. Any other result is intellectuals thinking too hard to try to impress themselves and probably missing basic facts in the process.