I assure you that hearing "pin you dependencies" is not why people create a requirements file using pip freeze. It's simply because that has long been how people have said to generate a requirements file, because Python spent much of its life lacking proper project dependency management.

And now it's extremely hard to get people to stop. There's so much info out there on the internet that says to use pip freeze that people are going to continue to run into and continue to learn to use.