Re: Apples and pears
Yes and no. I think that in terms of cause-and-effect you are putting the cart before the horse here.
There is nothing inherent about Arm _per se_ that means that they have to be highly-integrated. It would be perfectly possible to design an Arm box with generic PCI-e slots and an offboard GPU, disk controller and all the normal gubbins of a PC, and if you did that, it could run Linux and Arm-compiled drivers for all the bits.
But everyone is paying attention to Arm again because the M1 chips are both so bally fast, and run so cool, that they make for very powerful desktops and also for exceptionally thin laptops with exceptionally long battery life.
I owned an Acorn Archimedes in the 1980s. This is not news to me. :-) My £800 ARM2 box outperformed the fastest £10,000 PC my employers had as a demo model. (Nobody much bought that model, partly because it was ten thousand quid. Excluding keyboard, monitor and DOS, as was IBM's wont.)
Now, Apple has put the Arm ISA back in that position. It is just about the fastest desktop or laptop money can buy.
*But* the thing is that Apple has achieved that by extremely tight integration and most of a computer on a single SOC: CPU, chipset, GPU, all the RAM, all in one package. And packaging that allows 2 SoCs to function as conjoined twins, too.
It is the integration that has permitted the performance, but the ISA does not demand such integration.