If Linux users had "stepped up to the plate" and demanded their own separate PKI, nothing would be different, except that every system that shipped with Windows

If Linux users had "stepped up to the plate" and demanded their own separate PKI, nothing would be different, except that every system that shipped with Windows would be locked to Windows. Dual booting would not be a thing. I mean, your statement is self contradictory. Linux users demanded no signing etc. So, had the industry listened to Linux users, there would be no signing. We do not live in that universe. There are some vendors that don't have secureboot. They are e.g. System76. You can enable your own SecureBoot if you want[1], though some things may not work, like checking GPU firmware signatures, because they are signed by Microsoft only (there are other issues, depending on how deeply Microsoft is assumed in your system, see e.g "On some devices, removing either of these keys could disable all video output.") [1] https://wiki.gentoo.org/wiki/Secure_Boot https://wiki.gentoo.org/wiki/Secure_Boot