Yep, NIH.

DOS was primitive but the things you mentioned worked, even if they were a simulation. The end user was unaware, unless they needed real OS capabilites. In which case, why were they using DOS?

Cmd has a lot of improvements most people are not aware of because they were off by default. Still they refused to do further improvement necessary to make it very useful. There is a 3rd party shell called 4NT that is/was a compatible and very powerful replacement.