George Dyson is the son of the physicist Freeman Dyson, who worked at the Institute for Advance Study from 1953 during the time when von Neumann et al were building the IAS computer. He (George) gave a talk [1] in 2008 where he mentioned that he used to hang out at the IAS as a child and met von Neumann, Kurt Godel, and others. This probably explains his emphasis on the IAS and von Neumann. I do agree with the opinio…
Second, it was the first machine to feature any kind of an index register, a facility that was quite widely copied. You can trace the influence from the spread of the Manchester name for the facility: they called it the "B-tube", a reference to the internal structure of their own machine. (Already having an "A-tube" for the accumulator, and a "C-tube" for control registers, they used the first free letter.) And if you read through the computing literature of the '50s, you'll find frequent references to index registers using terms like "B-boxes", which are otherwise inexplicable.