Good point. I have to say I'm wary of that, recursive make is not a good idea, and the problem can't be fixed by building a better make, because the issue is that it breaks up the dependency graph and creates build problems.

Eg, if you have src/lib, and src/bin, and the src/bin project depends on the src/lib library, then in self-contained, recursively invoked makefiles (or anything else), you won't get a correct behavior when a header in the library changes.