That's exactly what a scientist would say. Engineers invent things because nobody told them they were impossible.

Or they go on wild goose chases. We call those people cranks, and there are plenty of them, such as all the people inventing perpetual motion machines (which arguably could be AGI).

Also, if you address the fundamental question first, Carmack may unlock something even more powerful than AI. As it is, he's just following the crowd.