I'm guessing you mean double the single core performance and not clock speed. Even Intel Pentium 4's from 2000 had higher clock speeds than Apple's M1 chips. The clock speed matters far less than what you can actually get done in a single clock cycle. Just looking at Apple's own products and their single core performance from Geekbench you can see they achieved around a 40% improvement in just single core performance [1]. So it's not just adding more cores. Apple has usually been the one to hold out on cores and usually has resisted adding more cores to the iPhone / iPad chips in the past and focused on better single core performance.

> Your average user is going to prefer double the clock rate of your processors to doubling the number of processors.

I disagree. The reality is that these days people are running multi-threaded workloads even if they don't know it. Running a dozen chrome tabs, Slack, Teams, Zoom, some professional tools like IDE's, Adobe creative suite, etc. adds up very quickly to a lot of processes that can use a lot of cores.

[1] https://browser.geekbench.com/mac-benchmarks