The annoying thing is that they can do this, but they won't offer some sort of extended support for old chromebooks. It seems like they could at least keep the user layer up to date and ship patches for critical vulnerabilities.
https://www.ifixit.com/News/30282/how-to-get-updates-on-your...
They charge in like heroes to extend the life of laptops with other company's operating systems and yet the four year old Chromebook that perfectly suits my parents' limited performance needs is being abandoned even though it's still fully functional.