Well I guess the problem with that is some people die while trying to obtain this natural immunity, or get really sick and clog up the hospitals etc
But if you survive you don’t need a vaccine
Look, I'm not anti-vax, but to me, a vaccine is supposed to keep you from getting the illness. It is a rare exception that you need the vaccine more than once. Tetanus is one such exception, recommended every 10 years as an adult or sooner in the case of a deep puncture injury or animal/human bite.