9700K 8 Cores 8 Thread vs 8700K 6 Cores 12 Threadsthe link you provided is saying a different thing...
BTW the 9th gen is an improvement over the 8th gen, on the same node, and the 9700K has 8 cores vs 8700K 6 cores.
The link I provided states this:
The top 17% bin can reach 5.2ghz and top 4% can reach 5.3Ghz, but those chip can also run 5.1Ghz don't they (hence 49+17+4 = 70%)
I can't exactly say "5.1Ghz and above" because only 21% of them can reach above 5.1ghz
For 9700K it's 38+9+1= 48% of chips can reach 5.1Ghz
So yeah 8700K has better overclocking headroom than 9700K and even the 10600K.