You (and many websites) confuse the difference between a 'bare' drive and an 'oem' drive.
In the drive world, a 'bare' drive is what you buy from places like newegg, mwave, etc. The drive has the same warranty as the retail boxed version but just doesn't come with a cable, screws, partitioning software, etc. 'OEM', in the drive world, are drives that are sold to system manufacturers like Dell, Gateway, HP, Compaq, etc., to install in a new PC. They have no warranty whatsoever. Dell/Gateway/HP, etc., warranties the drive along with the system and once that warranty is up, that's it.