Having a broad response via vaccination helps, even if you have antibodies from prior exposure.

Vaccination only provides an immune response for the spike protein, not a broad response.

People with natural immunity aren't even getting infected in any meaningful numbers, while fully vaccinated individuals are getting infected left and right.

If you are unvaccinated and have not had the disease, then if you get infected your prognosis is much poorer than being vaccinated.

If you are vaccinated and get infected, you have a better outcome.

If you are both vaccinated and have had prior immunity, see the discussion on other threads in this discussion.

If you are unvaccinated and previously got infected, you now have a much better outcome than being vaccinated, including from future variants of the virus.