Not really true because Apple can do it, higher margins and support OS much longer. The problem is how they design their OS and the amount of work required. Just look at how long time Windows support all hardware. It is possible, all is just software. They just need to take the hugh upfront cost of the software development that can even help other vendors and suddenly you can do a lot of about the big OS fragmentation problem. You want your latest OS to run on like 90% of all devices. Today, I guess that number is down to like 15%.

First day they sell one.

No, you need to look at OS API level which gets updated every OS. App developers just assume that based on age that they will no longer support older devices.