Where are you getting your pricing numbers? Let's take a prospective buyer today looking for new items.So you would argue that i5 @ 4.5 Ghz with DDR4 @ 3000 would be outclassed by i7 @ 3.7Ghz and DDR4 @ 2133?
Newegg: Z170 board ~$110 (cheapest is $90).
eBay: i5-6600K ~$200 (New, is $40 cheaper than NE) or (Newegg) ~$240 for a i5-7600K
Heatsink: $30 (Hyper 212 EVO)
Newegg: H110 board ~$60 (cheapest is $45)
eBay: i7-6700 ~$275 (New, is $50 cheaper than NE) or (Newegg) $315 for a i7-7700
~$335 for a i7-6700, which is 4.0 Ghz turbo 4C/8T
~$340 for a i5-6600K, which you'll likely get 4.3-4.5 GHz 4C/4T at safe voltages using a budget O/C cooler.
~$375 for a i7-7700, which is 4.2 Ghz turbo 4C/8T (same as 6700K at stock)
~$380 for a i5-7600K, which you'll likely get 4.6-4.8 Ghz at safe voltages using a budget O/C cooler.
And based on a batch of benchmarks in this thread, yes an increasing amount of games would benefit from a lower clocked 4C/8T CPU than a higher clocked 4C/4T CPU. In all the games mentioned in the video, only 1 game had a 4.8 Ghz 4C/4T ahead (and it was only ahead by <0.5%). The rest of the games had the stock 4.2 Ghz 4C/8T ahead anywhere from 5-25+%. With most up by around 10-20%.
And of course, as evidenced by a lot of the "Rig" signatures on Anandtech, most people don't get a lower end Z170 board. Realistically, most people overclocking end up buying a midrange Z170 board (which is around $150), which skews the pricing even more.