It matters because its not just adding electricity, its adding heat. Pretty clearly Apple can add a whole bunch of Firestorm cores to future M1 derivatives and still fit in smaller power/heat budgets that current generation Ryzen and Threadrippers operate in.

Maybe. I don't know enough about CPU design to argue with that. There are others elsewhere in this thread saying that a lot of the energy and heat goes on the communications systems and other resources you need more of when you ramp up the core count.

I suspect we'll never know. Apple have shown little interest in anything other than prosumer workloads for a long time. I doubt they'll be making an M1 server platform anytime soon.

I have to somewhat concede your last point. What percentage of AMD sales are Threadrippers in any year?

It's possible Apple just doesn't think the investment in a 30 core CPU is worthwhile and stops around 16 cores, which would still be higher than any i7 or any i9 ever made.