I recently had an otherwise perfectly fine eMMC-based Samsung phone degraded to unusable floppy disk speeds.
My guess is that their "RAM Plus" feature (aka swap) combined with the memory hungry modern android apps turned out to be a nasty timebomb. Which has or still is bricking millions of smartphones after a few years of usage.
Sounds like fixing that would be really bad for Samsung’s bottom line. Higher cost of materials initially, less frequent upgrades, and only a very small subset of super technical users even realize what the problem is.
