It's much simpler because you're using text files to define the expected state, the cli is there only to tell nix to figure out what it needs to do and to get on with it. Meanwhile with git you're manually doing each of the steps until you reach the desired state.
I only need cd ~/dotfiles/nix/ && nix-channel --update && nix flake update && home-manager switch for everyday package management. It's the nix version of apt update upgrade and install.
nix shell and nix run are pretty useful as well, and you'd want home-manager generations to rollback.
The confusion arises because there are 5 different ways to do the same thing, the non-experimental methods shouldn't be used even though they're recommended in the official docs, and you need to get lucky to get the info that you can use home-manager and that one liner.