A "casual" could button mash their way to success in DAO too, though. And regarding DA2, which that quote was supposedly relevant to - excepting the absence of tac-cam, the combat, tactics and mechanics were even more in depth than DAO.
For DAI - I would grant that some questionable streamlining happened in some cases, but I'm not convinced that it's dumbed down overall. Just different, mostly.
I'm a casual and play in the easiest. Yet that first ogier in Ostagar still owned me 6x. I certainly don't remember button smashing. I had to really look at AI and utilize tactical camera. Dont remember struggling like that on the same difficulty in DAI, even without healing.
I always play for the story so always on the easiest. Even now on TW3, Im on story mode.
The other point is that DAI was also successful both financially and critically acclaimed. Whether someone agree with the critically acclaimed part that is another story.
Financial success is easy to measure. If you want you can use the GOTY and People's choice awards as the existence of critical acclaim., but YMMV.
So how many games came out thats actually a competition last year?