The problem is game devs and engine makers don’t spend the effort to parallelize in the main loop everywhere they can.
You can get extra fps by having a faster single thread. Even still, if you had a 6 GHz single core CPU with a contemporary architecture then you would have an abysmal frame rate in a contemporary game. Those cores are used.
Except you don't get that it's not a meme, ideally CPU's were expected to scale into the 10-30Ghz range, that never happened because of the end of dennard scaling.
So yes ST performance is paramount, the only reason it's not is because CPU scaling hit a brick wall and because of power and leakage issues, when new materials become available that enable higher frequencies, you will see everything dramatically improve.
So no DX11 and Vulkan will not magically make all games faster, they are optimizations for graphics pipelines.
Most of today's games we're interested in run on 10year old machines just fine. If you think you can't run an i5 2500K /w a modern GPU and run 99% of all games you are clueless.
Most games are targeted at console specs and have held PC gaming back for decades.
Nothing against the product. A product name wouldn't ever stop me considering it as a serious choice, it just seems like a rushed decision that's unfortunately stuck with it.
Gamers never cared about the number of cores. Only recently has this slowly started to change. Intel is still king if you primarily care about gaming.
If you're split at all, single core perf on AMD these days is real close, and multicore Intel is just getting trashed (especially in any kind of price-per-perf metrics).
Desktop users might in addition care about heat (-> noise) being created in low load / near idle situations where those machines spend most of their time in.
It's not king in bang-for-buck, even for gamers.