This kind of thing is generally used to disallow downgrading the bootloader once there is a bug in chain of trust handling of the bootloader. Otherwise once broken is forever broken. It makes sense from the trusted computing perspective to have this. It's not even new, it was still there on p2k motorollas 25 years ago.
You may not want trusted computing and root/jailbreak everything as a consumer, but building one is not inherently evil.
You may not want trusted computing and root/jailbreak everything as a consumer, but building one is not inherently evil.