Not intrinsically difficult to use, I mean that the problems involved in implementing some ui concept may be intrinsically difficult or not (this can happen even when from the user's perspective the UI is simple/elegant). When they are, then you need appropriate tools.

And yes absolutely as I’ve said, if it’s possible to for some domain to have a basic ui do that.

Usually the difficulty of a user to conceptualize something has nothing to do with the complexity of the code.