Exactly! Jumpers with EEPROMS. I miss those. I recommended them often on Schneier's blog for a budget solution to boards with firmware update. There were also old mainframes that let users update the firmware by physically swapping it out much like we swap out a drive or SD card today. Cheap as chips can be today, there should be even more simple solutions available.

As usual, technology isn't the reason. It's marketing, profit per unit, and profit in maintenance phase.