Publishing papers is the way the academic/scientific world measures notability and/or competence. It's not the way the engineering world that Carmack comes from measures it. They measure it by building. But you're right, we kind of have to just trust that he has the expertise he says he does by his statements since he has not built any modern AI programs (that I know of at least).
> If he really thought that implementing gradient descent and basic stuff in a week long retreat gave him the chops to have serious conversations with AI researchers, he is really deluded.
This is not an accurate account of how he said he developed his knowledge base. Just how he got started so he could have conversations. He said that he spent a retreat learning the basics and then later in the interview he said he took the time to understand the 40 most essential papers in the field as related to him by a well known researcher. He has since largely put the last 4 years of his professional life into this. While we have no proof of his knowledge, given his intelligence and high competence in computer programming and math, I have no doubt that if he did put in the work he could achieve an understanding equivalent to that of your average AI researcher.
That said, of course it makes sense to be skeptical.