Because I banned it haha. There should not be more than one .env file. Our projects have a .env.example that has any overrides a dev might want to override but this list is kept intentionally very short. Meanwhile .env is noted in gitignore. I absolutely hate seeing an entire application configured with environment variables. Some? Sure, where it makes sense. Most? No, those should be in version control, secrets aside.
I believe in convention over configuration. Most of our apps have hard-coded config, with a concise/short and finite number of things that can be overridden (like 3-4 parameters, tops). Secrets get injected.
I do subscribe to the idea of the 12 factor app, but there is a line that needs to be drawn between env config which is more dynamic and more persistent config that should be baked in to the release.