I got the strong impression that those self-proclaimed "professionals" are more or less exactly the opposite: people who spend an inordinate amount of time plugging in dozens of different peripherals with random port requirements, fiddling around with the hardware, and running benchmarks.

For what it's worth, a Mac today is still as useful (at least for web development) as it has always been. Much more so actually because homebrew has evolved to be completely stable.

And while CPU speeds have been stagnating (mostly because they've reached "good enough" and then some), people are ignoring two major shifts in hardware that have significantly improved the dev experience: Retina screens and SSDs.