They do very different things even if the outcome is the same. You are not rollingback your system by downgrading each package. You are statefully changing your filesystem. Rollbacks in Nix and Guix are internet free, atomic and reproducible because they amount to changing the target of a single symlink
Maybe the point is that you cannot demand that the whole world knows the same set of concepts as you do. Otherwise just learn to remove cancer by yourself instead of forcing a person that studied decades to get down their trone and do their job