Having been a sys-admin once upon a time (2006-2008), these answers are straight forward. Servers used to have discrete ME cards which were paid add-ons. Competition in the early 2000s drove these ME cards to be integrated in the motherboard in order to better compete on the low end of the market. I’ve had servers I was only able to remotely fix due to the out of band management interface (more than once). They pain they fix is real.

The same techniques for managing server farms are useful for managing hundreds/thousands of corporate desktops. Being able to power up a desktop (“lights out” management) and re-image it at 3:00AM is very useful for example. You could also install 3rd party security products to the ME to provide higher level threat detection that’s hard for a rootkit to hide from. So once the work of getting an integrated management engine production ready was complete, it made perfect sense to use it in corporate desktops. It’s expensive to produce chip variants, so doubtless that further cost pressures on Intel lead to them putting the ME their core shared across all products. Plus, now IT admins can let the VP of Sales get the laptop she wants knowing they can leverage their System Center/OpenDesk/etc. console to manage it via ME.

So no, they aren’t a Fed backdoor. Those of us who worked in IT 10 years ago remember how the market drove Intel to add the ME. That is doubtless why many are silently conflicted. They don’t want to take a big step back. They likely are expecting/hoping Intel will “fix” the problem.