That we ever had "libre" desktops is an accident of history resulting from home computers, widespread internet access, and awareness of public key crypto arisin

That we ever had "libre" desktops is an accident of history resulting from home computers, widespread internet access, and awareness of public key crypto arising in that order. IBM took on the personal computer market and made the PC standard, which launched the chain of backwards compatibility that continues to this day. Because they did this in 1981, the idea of "secure bootloaders" was not on their radar. By the time anyone started thinking along those lines, the standard was well entrenched; this same standard gave Linux and other free OSs a relatively static target to hit, just as the internet was gaining ground (a force multiplier for hippie free-software types). Before PC clones took off, every home computer was a different design, OSs were specific to each model, and open alternate OSs were not really a "thing". For a glimpse of an alternate history where these things happened in a slightly different order, take a look at TI graphing calculators; each is a bespoke microcomputer using very 80s-ish technology (z80/m68k cpus, built-in BASIC etc) and each has RSA signed OS images, the keys for which were only factored in 2009. Even now that every single microscopic detail of the hardware is known, and the keys available, alternative OSs are niche and usually incomplete projects confined to a single model, because there is no standard to target. All we have now is a reversion to the natural order of things, permitted by the shift to "mobile" breaking all the rules and allowing all the norms to be reset.