Don Norman in 2005 wrote an article about how HCD can be misleading and how ACD could solve the issues that it creates.
It’s the first time I stumble upon ACD but I think it is the natural evolution of HCD: people will never tell you what you really need to do, but through observation and interpretation you can get an enlightened understanding of where to go. And I agree that it is never about the user himself, but more about the activities that he performs - and how to move from one to another one.
Some key frames Don Norman wrote:
Did knowing that the persona is that of a 37 year old, single mother, studying for the MBA at night, really help lay out the control panel or determine the screen layout and, more importantly, to design the appropriate action sequence? Did user modeling, formal or informal, help determine just what technology should be employed?
Human-Centered Design does guarantee good products. It can lead to clear improvements of bad ones. Moreover, good Human-Centered Design will avoid failures. It will ensure that products do work, that people can use them. But is good design the goal?
The focus upon the human may be misguided. A focus on the activities rather than the people might bring benefits. Moreover, substituting Activity-Centered for Human-Centered Design does not mean discarding all that we have learned. Activities involve people, and so any system that supports the activities must of necessity support the people who perform them.