I think this response is exactly what he was trying to preempt at the end of the talk, when he noted that these ideas in particular aren't his point: his point

I think this response is exactly what he was trying to preempt at the end of the talk, when he noted that these ideas in particular aren't his point: his point was that all of these ideas hatched in a short timeframe long ago, and they're all quite interesting and different (regardless of workability), so... why did they hatch then? The unspoken assumption is that fewer new, interesting ideas came out of the following decades, and the thesis he asserts is that this is because we have settled into smugly believing we know the whole territory of computing, rather than keeping the beginners mind, as people in the 60s were essentially forced to have. I think there are fair positions of opposition to his true thesis, but ignoring his main argument to point out that we don't use these ideas because we're, well, so experienced and savvy (or do use them in some spots, again go us) kind of seems like making his argument for him.