What are some of these viruses wiped out by mass vaccinations? Smallpox? Polio? Neither had nearly as many cases in a single year as Coronavirus (though they were much worse viruses). They are also very different viruses. Coronavirus may mutate slower than the influenza virus, but it still mutates much faster than Smallpox (which is a DNA virus) or Polio. Not to mention more cases of coronavirus = more chance to mutate.There was always "too much of" something, that had been eliminated by mass vaccinations.
The ability of that "something" to mutate is crucial here, and C19 isn't one of the too flexible types.
And we have no idea how long immunity will last either. In diseases that have been eradicated, immunity from vaccines lasts for years, even lifetime for some. The jury is still out on how long coronavirus immunity will last.