Let me just put this out there:
In the history of vaccine science, every effective vaccine that has ever been created has reduced or eliminated symptoms in a very high percentage of people who are invaded by the virus being vaccinated against AND has significantly reduced transmission of the virus from people who are vaccinated. For every past virus where a vaccine was created and a large percentage of the population (normally school aged and younger children) was vaccinated, the latter characteristic essentially eradicated the viruses from the face of the earth.
However, for this specific variant of SARS-CoV-2, which is still similar enough to the original to be called a "variant" and not a "strain," the vaccines still reduce or eliminate symptoms at nearly the same effectiveness as they did for other strains but have stopped preventing transmission from vaccinated people?
With the change in guidance, what the CDC is essentially saying is that, for the purpose of stopping the spread of SARS-CoV-2, the vaccines may as well not exist. Instead of saying I'm vaccinated I should be saying that I have taken a long lasting prophylactic against symptoms caused by SARS-CoV-2.
If this, in fact, the case, those who believe mitigation should be based on case numbers and community transmission are in favor of perpetual mitigation because there will always be cases and high community transmission.