I think the difference between software and configuration is a bit artificial. Whenever you install software, you are implicitly using someone else's config: the default. oh-my-zsh users are also using someone else's config, but it's better. What's the difference?

Edit: to clarify what I mean by the distinction being artificial, I don't see why you couldn't think of the kernel as someone else's configuration for your processor, or zsh itself as someone else's configuration for your terminal window.