I'm curious, why not?
Because an MKL license is required to redistribute MKL. If someone wants to include the binaries in their product they must acquire a license. An MKL-based binary wheel would be for end-users that wants to install and use NumPy. It would not be for those who redistribute NumPy as a component of a larger application. ATLAS and OpenBLAS are free, and Accelerate Framework is a part of Apple's operating systems. Those binaries can be redistributed by third parties without Intel's licensisng restrictions. But if you are an end-user installing NumPy for your own work you'd want the MKL binary wheel instead. Sturla