Sorry, can you elaborate on this? Is Skylake somehow performing multiple instructions per core per clock cycle somehow?
Basically, it's all a massive game to keep all the units of a core busy to execute the desired instruction stream as fast as possible. Over time, successive CPU architectures have gotten better at playing the game: better occupancy, more execution units, and more powerful units (SSE, AVX, etc), which translates into a greater number of instructions executed per clock cycle (IPC).
That's why a Skylake is much faster than a Pentium 4, even though the P4 might run at a higher clockrate. The Skylake has better IPC.
And as a side note: what Hyperthreading does is duplicate the part of the core that manages registers and instruction dispatch for a thread. So you have a second thread that can utilize any execution units that the first thread left unoccupied.
Bulldozer works somewhat similarly: two threads share a single core, and each core has a pair of integer execution units but they share a floating-point unit. So kinda like a Super-Hyperthreading, where they include a duplicate of (what they hope is) the most needed execution unit. Doesn't always work out in reality though.
https://en.wikipedia.org/wiki/Instructions_per_cycle
https://en.wikipedia.org/wiki/Superscalar_processor
https://en.wikipedia.org/wiki/Out-of-order_execution
https://en.wikipedia.org/wiki/Speculative_execution
CPU performance is largely "good enough" for most users. OS bloat has finally stopped: Win8.1 is just as fast as Win7 (and is more stable) and Win10 is faster and skinnier. Most users don't do anything intensive and probably wouldn't even notice if you substituted in a low-end processor. For those that do have big needs, GPU offloading has taken off in a big way.
This is kind of unfortunate in other respects. CPU performance (especially single-threaded) is extremely important for high refresh rates. At 144hz there's no margin for any weak link in the system. But I recognize that I'm kind of a niche user in that regard.