I thought there is a great level of control over these and none of these run Minix and connect to the network. The actual functionality that ME is supposed to provide is purposeful.
I did read them. Which part are you referring to? If it is GODSURGE then it is malware in the BIOS used by the NSA. I have seen nothing about China spying via motherboards, outside the propaganda hit piece Bloomberg wrote which everyone (even FBI and Amazon, etc) dismissed as total bullcrap.
With respect, what you linked to is a conspiracy theory that the ME is used in ways other than explicitly stated by Intel and unsupported by any evidence other than allegation.
"The Intel Management Engine with its proprietary firmware has complete access to and control over the PC: it can power on or shut down the PC, read all open files, examine all running applications, track all keys pressed and mouse movements, and even capture or display images on the screen. And it has a network interface that is demonstrably insecure, which can allow an attacker on the network to inject rootkits that completely compromise the PC and can report to the attacker all activities performed on the PC. It is a threat to freedom, security, and privacy that can't be ignored." - Hackaday
A part of my machine which I have no control over and which I cannot remove is a backdoor. Some would call that even malware. I don't care whether it has been solely used for the intended purpose which I can't even verify.
We saw photographs of this taking place in what looked like an assembly line or distribution centre, along with accompanying text from internal NSA presentation slides.
You mean not everyone believes the cold, hard truth?
That's unfortunate, because most of us here saw the evidence of this taking place.