Well if the requirements.txt is pinned to a specific version of a dependency of a dependency, you might not know or really care why that's set. But then this becomes a nightmare and dependency hell laterif you want a newer version of some package, and that newer version requires a bunch of newer packages and loses the others. At that point you probably will toss your old file and start a new one from scratch piecing together all the requirements with like pip freeze in a new virtual environment.

Sure you could omit the versions, but then everytime you deploy, you don't know what you're going to get and a deployment today would be very different next week with a whole bunch of different versions of dependencies.