One rationale I've seen is that uncontrolled spread and too many unvaccinated people overwhelms the hospital system, thus causing dramatic harm to people who ne

One rationale I've seen is that uncontrolled spread and too many unvaccinated people overwhelms the hospital system, thus causing dramatic harm to people who need non-COVID related treatments. This dynamic played out in the US just a few weeks ago. That last wave had a larger proportion of hospitalized people who were younger and, in theory, less at risk because that group was less vaccinated as a whole. The vaccines do reduce spread some, but they also keep people out of the hospitals.