Secure Boot (on ARM) restricts my ability to run whatever the fuck I want
on my device. I do not see how this is not Digital Restrictions Mismanagement.
DRM usually refers to mechanisms to digitaly manage rights of content, SecureBoot merely checks that a bootloader is signed by specific keys. Just ensuring people know what's what.
My point is that it's one and the same. You're making distinctions where
there are none. Software which I run on my device is content, too. Denying
me the right to change or modify that content is the very definition of DRM.