This is true, however it doesn't make the point irrelevant. 1. Beyond difficulty of porting blobs, you might well also simply get your updates from a custom RO

This is true, however it doesn't make the point irrelevant. 1. Beyond difficulty of porting blobs, you might well also simply get your updates from a custom ROM faster than you'll get them from the manufacturer, even if it's still supported. That in itself is an advantage. 2. Backporting updates to third party components can be simple (assuming a stable ABI/API); the easiest case is probably that of just dropping binaries from a similar phone that did get updated into a zip file and then flashing it. Look at busybox installers, for example; all you need is a version compiled for your hardware. Java components can sometimes be changed as well (see xposed). This works on desktop systems as well, sometimes: I've been able to 'fix' older games into working just by dropping a newer version of a dll into the game directory (directx, openal, etc)) 3. Maybe the company is just stupid. Motorola (or is it Verizon?) has tried Marshmallow for the Moto E2 in Europe, but not in the US. I'd expand on this but I'm on mobile and I'm lazy.