Microsoft is the reason why this practice exists in the first place. Their Windows distribution contracts with OEMs say that all computers that an OEM ships mus

Microsoft is the reason why this practice exists in the first place. Their Windows distribution contracts with OEMs say that all computers that an OEM ships must be preloaded with an OS (likely for the piracy issue you mention). Shipping FreeDOS allows OEMs to sell computers to people who don't want to pay for Windows licenses while also not having to provide support for Linux (or some other alternative OS).