This isn't really true. For instance, it's been shown that mutations are far more common in immunocompromised people (many of whom cannot even take the vaccines

This isn't really true. For instance, it's been shown that mutations are far more common in immunocompromised people (many of whom cannot even take the vaccines) where the virus can just camp out for months and train itself against the human immune system. So one particular host might serve as a more fertile environment for variants than thousands of others combined. https://www.washingtonpost.com/health/2021/03/11/immunocompromised-patients-covid-variants/ https://www.washingtonpost.com/health/2021/03/11/immunocompr...