If it's hundreds, I'll agree with you, obviously that would be a huge effort to migrate.
But you made the argument that adding another build dependency is somehow difficult or undesirable which I can't see; the tool is installed in seconds on all major OS-es and package managers.
So let's not conflate those two separate things, yeah?
`make` running fine is the hill I'll proudly die on. Or simply put, I'll disagree forever. It's full of subtle issues that I got tired of tip-toeing around. It's a never ending black hole of programmer time.
And yes, `just` isn't a build system per se, it still requires something to track modified source files and whether they map to the requisite build artifacts. Good for C/C++ and maybe stuff like Latex -> HTML but outside of that it's obsolete and thank the gods for that.
If it works well for you, cool. As mentioned up-thread I wouldn't attempt a switch with hundreds of Makefiles already working fine either.
But I'm very happy to tell you that your case is the vanishing minority. Happily the world has moved on.