"Secure Boot" doesn't make root non-uid 0, and can't keep root from 
controlling system devices, even uploading unsigned firmware to peripherals. 

While it's true that a completely secure software chain doesn't really exist yet, we are slowly going in that direction, because it is just inconceivable otherwise in the world with billions of autonomous IOT devices---the consequences of a worm-type insecurity that would subvert a significant portion of Internet-connected devices are just too scary.

For instance, one possible solution used e.g. for a secure BIOS updates is to prevent loading firmware directly, and instead load it into a separate flash area. Then, reset the system:

• existing certified firmware boots and finds the updated firmware
• new firmware is measured and verified
• if it passes, the old firmware copies and activates the updated firmware

So you see that you can't subvert this even with UID==0. Same thing for controlling system devices---with secure software chain even the applications can be certified and controlled. THis is not your or my desktop system, of course, but there is a need for systems like this.

When I hear you say that this takes away the ownership of our computers from us, I think that it's got to be this way for a large part of those billions of systems---as the saying goes, we have to stop thinking of computers as pets, and start seeing them as cattle. We can still have pets as well, but there has to be a way to herd cattle.