I'm a layman on this, but reading IBM's rebuttal, it seems that they're saying "you can't say that a conventional supercomputer would take 10'000 years because you haven't accounted for spilling to disk and other optimisations".

I understand that some of these optimisations might be on the processing logic, but doesn't this end up being like comparing apples to oranges?

I understand that there's also what seems to be technicalities around what is "quantum supremacy", but I assume that on a 'processor against processor' basis, this is still significant. Am I oversimplifying things?