Funny you mention ksh since I've been trying to kitbash ksh93 into being
able to compile with make instead of the funky build system it currently
uses, without a lot of luck.
IIRC, Korn used make when developing ksh, but then shipped it with a /bin/sh script because it was more portable than make was in those days (and still is; there are tools that warn you to use gmake on BSD). After all, a build process (unless it is interrupted) just needs to build, it doesn't need to keep track of what has already been built.
That said, I have no idea what the state of the build process is now.
America is not a morally pure country. No country ever has been or ever
will be, but in democratic countries you get things done by compromising
your principles in order to form alliances with groups about whom you
have grave doubts. --Richard Rorty, Achieving Our Country (1998)