I even managed to give gnome2 to my mum at one point and she remarked how nice everything was and easy to find. I had more difficulty than she did since I was much more into computers and had learned all the intricacies and idiosyncrasies of Windows.
Then gnome3 came and was a huge regression in terms of flexibility, ease of use, aesthetics and performance.
Plasma was the same, though, subjectively it looked better and was a lot less antagonising than gnomes radical redesign, it was still really heavy and buggy compared to kde3 (or whatever the predecessor was, I think 3).
Plasma/KDE was also very windows-like, so I don’t buy the argument that Microsoft was the cause, it was mostly gnome devs thinking that they could get a radical touch-first redesign in before anyone else.
This is a very long way of saying: the parent is correct in my opinion.