Another way of looking at it is that it probably takes a really long time to bring up an operating system to the point where it is production-ready. It would b

Another way of looking at it is that it probably takes a really long time to bring up an operating system to the point where it is production-ready. It would be easier to do if you can target one hardware platform that does not change so that you don't have to also shift gears. If you're building the Great Pyramid, you don't want to also move it to a new construction site when it's half-completed. Launching on hardware that was already released could mean they gave themselves that time. By the time they're finished (now), the hardware is old.