> Vaccinated people are also less likely to collapse the local medical system in surges because their disease course is less severe

But once you have primed your cell immunity with exposure (vaccine or natural), the benefit of repeated boosters is negligible. Protection from infection is affected by changes in variants because only Ig neutralizing the spike can block infection. Cell-based immunity, although it does not prevent infection, is more resilient to these changes (the homology in the SARS-CoV-2 proteins outside the spike is around 80-85%). Also, memory cells last for at least two years after exposure (A.Sette's group works).

IOW, less severe versus an immunologically naive person. But at this point, with 95%+ seroprevalence, these scenarios are becoming very rare.