They've been declining for years, and been selling defective parts for years.
I work at a local small privately owned workbench, and for years Dell's computer's motherboards BIOS, by default, has SMART error reporting turned off. If you turn it on, and go to "restore defaults" it will also reset it to off. I turn it on in every case in hope that it will save someone's important data, which I have seen SMART do, so that they can backup their data before the drive completely fails. I discovered this when someone brought us a maybe 4 month old Dell desktop system who's filesystem, and this windows, was ripped to pieces. Running a diagnostic tool, in this case SeaTools for DOS on it, revealed SMART was tripped, and it fail read element tests, so bad sectors. Seeing SMART was tripped, I wondered why the BIOS did not report it, as most modern BIOS have it and it is enabled by default. I looked, and found the above results.