For PCs you do control MOKs, for now.

For mobile devices, or for devices like Chromebooks, you don't. It is only matter of time, until PCs change too, with apologies like 'nobody uses it anyway, why complicate things' etc. The frog must be boiled slowly, otherwise it backfires.

Chromebooks are explicitly designed to permit re-keying, although it does require you to physically disassemble the machine[1]. And if anything, we're seeing more user-unlockable mobile devices now than we did in the past. At the high end, server vendors want to maintain control of their keys, and there are large companies who want to do the same for corporate desktops and laptops. At the current rate, the frog's going to die of old age before it notices anything.

[1] The reasons for this design choice are understandable, even if I disagree with them

Not all Chromebooks require physical modification for re-keying. (The Dell Chromebook 11 doesn't, for example.)