Not sure why author writes using negative language about the fact that Android cannot be remotely updated? To me that sounds like an agenda to encourage the use of less privacy conscious operating systems. If the OS can be remotely updated, nothing stops bad actor from updating particular phone with a keylogger to bypass any end to end messenger a target is using and so on. Remote update is a great option if it is initiated from a trusted source.
Let's assume that you are correct. I am now holding a perfectly-fine Samsung Note 3, purchased new in 2013 and has never had a broken screen. To which trusted source can I initiate a remote update?
LineageOS allows users to stay on a reasonably secure up-to-date android version. Unfortunately, the initial install process is not user friendly enough for the average person who owns one of these devices. That's the barrier to entry. But once installed, this wouldn't be a problem.
Honestly, Google should require as part of the Play Store certification that vendors ship their goddamn drivers in a quality that is acceptable to upstream Linux, or at least get them to staging quality.
The situation exists entirely because Google created it, they designed a HAL (hardware abstraction layer) with the intention of letting device manufacturers design devices while skirting GPLv2 requirements.
It's infuriating that device manufacturers refuse not only to provide a viable update scheme for their devices, but that they lock out any chance for a FOSS solution to the problem either.