" then other people criticise it, and instead of replying to the critique in a sensible way"
Which is what people criticizing secure boot and anti-tamper chips exactly do, especially if Microsoft is involved. Especially the OP was babbling about "boot sector viruses" (UEFI AFAIK has no boot sector at all) which showed how sensible and technical was his critique. And your attempt to shutdown my argument it's exactly applying the strategy you pretend to blame.
Explain how secure boot takes control away from you. You can disable it. You can load keys. Don't believe me? Maybe you will believe http://www.linuxjournal.com/content/take-control-your-pc-uefi-secure-boot
Sure, some system may be locked down. Don't buy them. They are not designed to be extensible and programmable systems. Sometimes it may be useful. Would you like a critical system allow easy tampering with? Sometimes it's just "commercial control", true, like a phone or a console. If you don't like them, vote with your money, don't buy them. Looks they may be very successful, though.
Why should you have the private keys on the same system??? Keep them on external (encrypted) storage, sign the code, remove the storage. Heck, they can (and should) be on a tamper proof external cryptographic device.
So, once again, critiques looks to stem from a lack of knowledge, using second hand incorrect information only. Is pointing out factual incorrect statements, being out of arguments? Or you have "alternative facts", which are so common today?
And still most critiques about secure boot are FUD about not being able to run Linux (and since secure boot was introduced, how many weren't able to run their preferred distro of LInux), "commercial control" - yes, it makes harder or impossible to run pirated copies, where's the issue? After all you all run Linux, not a pirated copy of Windows, don't you?, you use only open source software, you don't try to pirate PS or XBox games, don't you?
And about MS controlling the keys and refusing to allow other OS to run (it will hit an antitrust wall immediately, especially in the EU).
And that all utterly blind to what from a security perspective being able to spot rogue code from the very beginning means.
It's just an ideological and political position - the FSF/GNU one, after all - there is no sensible and technical critique, it's just the fear of being controlled by the evil Spectre who's attempting to rule the world, and will be saved only by the open source militants, especially those who just use open source because they don't have to pay for, while attempting to crack what they like but they don't want to pay for, but still hypocrites enough to try to shield under a false "freedom" cloak.