On the other hand, make invokes well known shell commands; I already know what they do, when I see them used.

If you are invoking your functions (or functions imported from random library), I have to check them for what they do.

it is possible that if you need to do that much in a makefile that you are running into shell incompatibilities then perhaps you are attempting to cram too much complexity into your build system and perhaps should be using something like Docker to decrease incidences of “works on my machine/os/distro/et c”.

(I am aware that this advice does not hold true in all cases; just that for many of them overly complicated build systems is a code smell.)

To be fair, at the core much of what you're going to be doing is invoking command-line tools. I mean, most compilers are invoked as command-line tools.