More importantly, how do those cattle become cattle in the first place without BMC? How do you turn them into another breed of cattle without BMC?
Not that it can't be done... but that's a system dependent on the hardware doing the right thing, as opposed to a system that can tell the hardware what to do every step of the way.
How are you triggering the machine to PXE boot? How are you recovering from situations where the machine becomes unresponsive or needs someone to look at a console to see why a failure occurred?
I hope to see such a thing some day. The code quality and support lifecycles for these things are horrendous.