Make is also a highly discoverable entry point to a project.
A Makefile with tasks that just run external scripts is much easier to find than the scripts directly. Add some help texts and it’s a great DevEx multiplier.
With a Makefile I can generally just run `make` or `make <tab>` to have a feel for what's available. It's right there on my terminal, which is usually the first thing I interact with when I open a repository. If enough of the engineers use it, it stays up-to-date as it gets fixed and updated along with any other changes.
Documentation OTOH has a tendency to be forgotten and left for dead. IME this is especially true for internal documentation, and the closest to the code the docs are, the less attention they receive - since higher level documentation is more likely to be consumed by people outside of the team.
With a README, I need to:
* remember to read it
* trust that it will have the information
* trust that the information is up-to-date
* finally, figure out paths to scripts, arguments and/or copy-paste commands