AIUI is just that DOS was complying with the standard, while Unix had decided to break it. The standard was designed for physical teletypes and has a bunch of issues (like, what do you do with LF-CR?) but its not unreasonable of DOS to have stayed with it.
Apparently the LF vs CR+LF printer control code standard arose ~1965 as ASA (pre-ANSI). Neither Unix nor Microsoft created the standard, and of course ASCII didn't either.
