> Put another way, the M1 achieves half the multithreaded performance of the 5950x while using less than a quarter of the energy. That's pretty impressive.

That isn't impressive, no. Power scales non-linearly with clock speeds (and thus performance across a particular CPU design). Compare a 3700x vs. a 3800x for example: https://www.anandtech.com/bench/product/2665?vs=2613 - Huge increase in power draw, barely any performance increase.

You'd have to compare at equivalent power levels to draw a meaningful conclusion like that. Especially since the 5950X is paying power for things the M1 just doesn't have at all, like the large amount of PCI-E lanes. But otherwise for a wall-powered system quadrupling the power for doubling the performance is a quite straightforward "yes please!" tradeoff to be made. Often the gains are much smaller than that.

Of course the M1 also isn't designed to excel at heavily multithreaded workloads having "only" 4 big CPU cores, so it's an unfair fight in that direction as well.