I agree fully with the OP, in particular I find it smart that he wraps anything in a top-level makefile, even if other, more sophisticated build tools are used. The advantage is standardization, not having to remember anything and to know that if you wrote it, you will just be able to type "make" and it will work.
Let's say a C person wants to compile a Rust project, they would not have to look up how cargo works, but could simply type "make" (or "gmake"; I don't use GNU specifics, but try to be POSIX compliant, even if it is certainly true that almost 100% of makes are gmakes).
Thanks for proposing the use of the timeless "make" as a sort of top-level build system driver; this will probably still work in 250 years.