their pricing means it is basically never worth buying and upgrading versus just buying a new laptop (seriously, run the numbers. You basically save 10 bucks over two generations of shopping at Best Buy).

Maybe so. But the big difference is, you can upgrade iteratively rather than taking the entire hit of a new device all at once. So I can buy all of the individual components of my next laptop a few hundred dollars at a time over the course of a couple of years, and use them as I get them. By the time I've ship-of-theseus'd the whole device, I may have spent the same amount of money on that new computer, but I paced it how I wanted it. Then I put all of the old components into an enclosure and now I can use it as a media center or whatever. Plus, if something breaks, I can fix it.