As such, where minimizing differences by processor was clean and relatively straightforward for x86, expecting it to continue to work well for ARM is nonsensical. I really think Linus is missing the forest on this one.
Not true. Pretty much all of us maintainers agree that the duplication of code and infrastructure in arch/arm is ridiculous. It has to be fixed, and we're actively working on it. Linus was perfectly correct in his statements.
Regardless of whether a mission expands or contracts, administrative overhead continues to grow at a steady rate.