The CI angle was my first bet as well. You build and test in the cloud nowadays. Heck, you might develop on MacOS, and deploy on Linux. There are places where

The CI angle was my first bet as well. You build and test in the cloud nowadays. Heck, you might develop on MacOS, and deploy on Linux. There are places where it matter, SIMD processing for instance, or low-level kernel development. But if you are on any kind of VM system, or ecosystem with a good compiler history, you are likely to have a smooth ride. If, in addition, the price point of the ARM machines are at 2/3 of the X86-64 ones, you are in trouble. x86 had another important point up its sleeve: price. And I might expect this was a confounding variable in Linus argument. Not only did you have the x86 at home. It was also like 1/8th of the price of an Alpha, PA-RISC or Sparc machine in price point. And at the time, x86 was dog slow compared to Alpha, and its I/O was laughable compared to HPPA/Sun. If you have a sizeable invoice at AWS, and you can shave the EC2 price by 2/3rds, you are going to have a lot of wiggle room to make sure your system runs on that aarch64.