We are stretching the metaphor thin, but surely the progress towards an atomic bomb was not measured only in uranium production, in the same way that the progress towards a QC is not measured only in construction time of the machine.

At the theory level, there were only theories, then a few breakthroughs, then some linear production time, then a big boom.

> Something doesn't add up here.

Please consider it might be your (and my) lack of expertise in the specific sub-field. (I do realize I am saying this on Hacker News.)

You can already factor a 6 digit number with a QC, but not with an algorithm that scales polynomially. The graph linked is for optimized variants of Shor's algorithm.