There are many Chromebook lines that are similar to phones in that you can't just install Linux or a new version of Windows once Google stops supporting your hardware.
Uniformity is important for management of fleets of devices, free refurbs arent free — they require more labor.
Refurbing broken old dells won't solve the unformity problem. The point of Chromebook is that they are uniform from a fleet management perspective.
And the point of
Chromebook is awesome from a management perspective, but you need to buy Neverware to chrome-ify the boneyard stuff, and you still need to deal with batteries, power supplies, etc.
The board level components (memory, CPU, etc) are not individually replaceable as the boards are designed by Google, not the OEMs.
This all assumes that you are not paying for repair labor, however. For very inexpensive Chromebooks, The repair technician's time may cost more than a whole new device.
Disclosure: Chrome OS engineer, but my positive opinions about Lenovo devices are my own.
Sort of like how many people who ended up in the corporate IT support/management field started out working as computer lab support techs in college, or before that, kids who worked in the high school auto shop (remember when those existed?) sometimes ended with good careers in auto manufacturing.
I always read about employers who have a hard time finding good technicians.