I would totally agree with this assessment, 100% under normal circumstances. But lets examine those normal circumstances.Likely, but the fact that all that stuff is integrated (or rather stacked on top of) into the processor for the mobile chips, maybe that isn't the way they'll do it for the big pro desktop chip - the Xeons don't have integrated graphics the way the desktop & mobile Core chips did, for example.
A "Pro" AS desktop that doesn't have user-upgradable ram, graphics etc is a non-starter, no matter how good the CPU is, it would literally be a step further back along the road of the 2013 trashfire.
Turning people's $10k machines into stranded assets, by releasing a radically higher performance AS machine with no upgrade path, seems like a great way to burn the bridges they've spent so long trying to rebuild.
The only reason that people are still getting use out of their 2008 cheese graters today is because intel CPUs have not progressed very far at all. The GPUs on the other hand have upgraded massively, and being able to replace the GPU with regular upgrades has given people long life out of old machines.
But what if ARM based CPUs like the M1, M2, M3, etc had the same upgrade progress as GPUs? If so, then older machines don't need to be upgraded as frequently, because you'd need to replace the whole motherboard and system to get the best performance upgrades.
I'm not a fan of systems that can't be modified. I think that it is inflexible and thus problematic. But the future of computers might look very different in the 2020s than it did from 2008-2020 if ARM takes us in a wildly different computer progress direction.
RAM on the other hand is just a capacity thing, since the speed is generally limited by the bus of the motherboard / CPU. If you bought a machine that was already maxed out, unless you get lucky and new chips with higher capacity for your slot size and speed are developed, you already have the best there ever will be for your machine.