Oh there certainly is. And there’s a reason Apple works hard for really fast single core performance. For a lot of tasks it still matters.
I suspect one of the issues is that pushing the clock is a really easy way to get an extra 2% so you can claim the crown of fastest or try to win benchmarks. It’s easy to fall into a trap of continuing to do that over and over.
But we know the long-term result. You end up blasting out a ton of heat and taking up a ton of power, even though you may only be 10% faster than a competitor who did things differently. Or worse you try to optimize for ever increasing clocks and get stuck like the Pentium 4.
As said up thread, no one really compares Apple CPU speeds with megahertz. That’s partially because Apple doesn’t talk about it or emphasize it which makes it more difficult, and partially because it’s not like you have a choice anyway.
It would never happen but it would be interesting to see how things would develop if it was possible to simply ban talking about clock speeds somehow. What would that do to the market?