The hardware is way ahead. Look at it this way; Intel CPUs haven't had any truly significant changes in over a decade now, at the root of it all the core architecture is the same as in the first generation of Core CPUs, I don't know much about AMD but their latest stuff is doing insanely well, possibly for this reason. Meanwhile, consoles are using slightly modified AMD mobile processors and getting insanely good performance out of them.
In other words, in terms of hardware, the PC side of things is pretty sedate and consoles do a lot with not much. That points to the software being the bottleneck, otherwise we'd see rapid development in PC hardware.
The diminishing returns and difficulty of die shrinks don't help, of course, but we've only recently seen >quad core CPUs in Intel consumer CPUs when their Xeon range has had hex, octo or more core options for at least a decade. Had there been a use for more cores earlier on we would've had the opportunity to buy them, but the software to leverage them was lagging way behind.