Comment by userbinator

I believe it was in the mid-2000s that BIOSes started storing configuration data in the same SPI flash they occupied, and UEFI just continued that trend and expanded on it. That removing the CMOS battery no longer clears it automatically is both a good and bad thing, and another problem it's created is that flash has a limited number of write cycles - and every time the system is booted, and possibly even while running, writes occur.