Of course the major distros like Ubuntu can boot with the default secure boot keys.
I have a feeling x86 manufactures would face considerable backlash if they tried to lock down SecureBoot in a manner where it's impossible to disable. (and yes, I do know there are some Microsoft devices that are already setup this way, but the majority of manufactures do allow control over SecureBoot). Then again we have Intel ME on all our machines and that's somehow still okay, so maybe you're right.
There was "considerable backlash", to say the least, to every little step along the way to the current, ridiculous reality you describe.
No one cared about our objections. The voices of those that care about free general purpose computing are not important to those who make the decisions.
We are frogs and we are being boiled.
This happened before with radio and TV signals. A great way to have peer to peer comunication, with local TV's and radios, ended up being regulated.. and in our culture, its normal to sit in front of a TV, and have a few monopolies to choose what we will watch.
And right now its unthinkable to revolt to those kinds of laws that forbid us to transmit content, as we accepted as normal (where's the cultural aspect of it, shaping our behaviour).
The same will happen to the next generations if we dont take a stand against this. Normal users wont understand the social, cultural and political implications of this. Companies like Apple defining what you can or cannot use, listen, see or install in your own device.
I don't think this is comparable. Radio and OTA TV needs to be regulated by a central authority or it won't work for anyone beyond a certain level of technological penetration. There's a set amount of data that can fit in the amount of spectrum available, and a radio station is transmitted to everyone whether they request it or not.
You've always been free to create and distribute VHS and cassette tapes because those don't eat into the amount of spectrum available to everyone.