because _some_ specs(acpi, bios-stuff, nforce chipsets, intel's uhci usb, (just to name a few) ) tend be inaccurate, incomplete, Hardware-vendor found a better way to do sth. better without saying it to the spec. writer, the Big MegaShit Company messed it up, or just written by a complete idiot!

(usb is fine now, acpi _works_ too to some degree but there still some broken laptops around!).