Of course, we can never stop all mutations. However, for mutations to be useful for the virus, they do need to happen at an evolutionary scale. Especially because we're lucky that SARS-CoV-2 mutates much slower than Influenza and HIV.
If the rate of transmission reaches the elusive herd immunity, the time-frame for the virus to evolve into evading vaccines grows significantly longer, even with a non-zero mutation rate.
Lastly, antibodies created via the mRNA vaccines have a broader binding affinity to different variants than those from natural immunity [1].
Again, the goal is to not eradicate, but to scale it down to the point where it is statistically not a threat.
Your original point was we got lucky with the Delta variant because our current vaccines still work.
I'm saying it doesn't matter - even if we had a 100% vaccination rate, some new variant will develop someplace that's being ravaged right now (say, India) and spread to the US eventually anyway. If our vaccines still work - great... if they don't, well.. where are we then?
Lastly, the numbers already indicate it's statistically not a threat to the overwhelming majority of the US population as-is.
I wasn't talking just about the US, I think we need very high levels of vaccination everywhere to make it statistically not a threat. We need to control the spread of the virus to levels where it's not mutating at evolutionarily scales, _everywhere_, and the only way to effectively do that is vaccines.
It's not a threat at this very moment, for this very point in time, but since we're allowing the virus to spread at such evolutionarily scales, inside and outside the US, a new variant popping up that evades vaccines is statistically very possible, and pose a significant threat to my own and society's well being.
I'm trying to argue that this is not a personal choice issue, rather a public health one.
If the rate of transmission reaches the elusive herd immunity, the time-frame for the virus to evolve into evading vaccines grows significantly longer, even with a non-zero mutation rate.
Lastly, antibodies created via the mRNA vaccines have a broader binding affinity to different variants than those from natural immunity [1].
Again, the goal is to not eradicate, but to scale it down to the point where it is statistically not a threat.
[1] https://pubmed.ncbi.nlm.nih.gov/34103407/