Also, Apple doesn't make its own A-series processors - it uses TSMC for that.
I don't know enough about this, but the GP's argument of "Intel hit the wall first because they were the first to reach that level of performance" makes logical sense to me.
Yes, Safari, but iPhones do compete with your average desktop processor (not the top end).
https://macdailynews.com/2018/09/23/apples-iphone-xs-is-fast...
Don't forget that Intel CPUs have things that A CPUs are missing like QuickSync, AVX2, massive PCIe interconnectivity.
Whether the A-series CPU could be modified into something competitive on that front is yet to be seen. Whether this actually matters considering the state of our compilers and software development is yet another question.
And as you said, you're comparing the top-of-the-line iPhone to an "average" CPU.
They really don't. A12 added a couple of instructions for floating point conversions, but contrary to claims making rounds on Twitter at the time, they were not even generated by WebKit when the benchmarks were run.