> some point on the spectrum between "commit your dotfiles to git" and Nix

That would be configuration management tools such as Salt/Puppet/Ansible/Chef.

They were popular ten years ago, and gained a lot of exposure as the devops movement gained ground, but they never stopped being useful.

Having your non-running state defined declarative is powerful, and if you can define a single source of truth for entire distributed systems, that suddenly makes you able to reason about state on whole systems.