[derefr]

FAT is for weak little cost-optimized embedded-microcontroller devices that write one file at a time to an SD card — which is something we're still building to this day, in the form of IoT devices. We don't really have any better option for this use-case; every newer filesystem is either non-portable, or assumes stronger hardware such that the overhead of using it on these devices would be huge.

I would note that one way to work around the cost-incentives of IoT manufacturers, would be to encourage them to externalize the storage-layer costs from the device's BOM, by focusing on getting "object-storage oriented" NAND flash controllers pushed down from enterprise to regular retail availability. That way, all the filesystem-layer smarts end up living in the SD card itself — which is sold separately. (It'd be sort of a second coming of the ancient Commodore 1540/1541 paradigm, where the disk controller presented not as block storage, but as, essentially, a single-user serial-attached NAS.)