Re: CUA
For me the ideal system starts with "walk-up-and-use" that covers the basics, and which many if not most users may never need to go beyond. i.e Start programme, create product, save/print and close. Then offers something more complex, with clear and simple explanation of what it's for and instructions how to start to try and do it. For users who want to make more use of the software. Ultimately pointing users to a pro-Level with full explanations of what the software can do if used to its full and explanations of how everything works. For uses who need to become experts and manage edge cases.
This is seldom the case though. Too often the user ( e.g. me) is presented with a page full of options and panels - none of which is obviously "get started".*
And helpfiles that seem to explain how to use individual components without actually saying what they're for, when to use them and how they might be useful
An obvious example ( to me anyway) is layers in graphics software. Because you can't see a layer so it's not obvious that it's there. Until you try to do something simple, like copy and paste, but you can't because somewhere along the lines the programme has added a new layer and the bit you want to copy is secretly buried in the lower level even though you can still see it. Or you try to paste and you can't because the programme has added a new kind of layer that you can't see is there and which has a purpose.
In effect there's an awful lot of software that dumps the newer but generally IT competent user into the area of "I ought to be able to do this, but I can't because it just won't let me and I don't know why"
*"Wizards" were created as a work around for this. But too often they seem to be guides on how to do something you don't want to do, in a way that's far too complex to get a handle on for future independent use.