That's because it is a complex and messy problem. Especially MDMs that try to unify the experience for fundamentally different platforms like Apple's and Google's, and even Microsoft's. I think if it's a platform-dedicated solution it actually does have the chance to be much easier to operate. So this thing by Apple looks interesting.

I would expect Apple to actually simplify the problem and not overreach and just do activation / provisioning / deactivation / lock and none of the other stuff MDMs try to do that introduces the complexity.