I've had a lot of people tell me that DOS is a bad OS. I've had a lot of people tell me that Unix is great.
OK. DOS is a single user OS. Unix is a multiple user OS. DOS does not multi-task. Unix does. DOS was never meant to be a multi-user, multitasking system so it's unfair to criticize it for that. If you need multi-user/multi-tasking, move on.
Except for these two differences DOS and Unix seem to work alike. A mathematician would say they are isomorphic, i.e., different words and symbols are sometimes used for the same thing. E.g., one uses where the other uses /. A trivial difference. They are both command line operating systems that store files in a hierarchy.
So why do people criticize DOS?