I find it really useful for development. For example when I configure nginx + a service, if it works in my local env, I have to run one command and I'll have the same in prod, and I don't have to debug in the server. Also is useful to keep track of the OS dependencies.

But it ends up being a matter of preference, I could still do it without it, but I'm used to it now, for some reason I feel that it makes my systems more "reproducible" in a simpler way.