I think people underestimate the challenges involved when building software systems tightly coupled to the underlying hardware (like if you are a team tasked with building a next gen server).

Successful companies in the space don't underestimate it though, the engineers who do the work don't underestimate it, and Linus doesn't underestimate it either.

The domain knowledge in your org required to mitigate the business risk isn't trivial. The value proposition always needs to be pretty juicy to overcome the inertia present caused by institutional familiarity. Like, can we save a few million on silicon? Sure. Do we think we understand the challenges well enough to keep our hardware release schedules without taking shortcuts that will result in reputational impact? Do we think we have the right people in place to oversee the switch?

Over and over again, it comes back to "is it worth it", and it's much more complex of a question to offer than just picking the cheaper chips.

I imagine at this point there is probably a metric fuckton of enterprise software what strictly dictate that it must be run on X86. Even if it doesn't have to. If you stray from the vendor hardware requirements, bullshit or not, you'll lose your support. There is likely friction on some consumer segments as well on the uptake.