I find it surprising (in a good way) the author could be a programmer for 26 years at Apple. A lot of corporate places I've worked at are always pushing you to progress in to leadership positions; if you aren't moving upwards then you are "managed out" which I always find really sad, the idea that simply being good at your job is now no longer enough. Good on Apple if they don't follow this type of thinking.
If every developer moved "up" to management after a few years, only mediocre programmers would be actually writing code (which is partly true). I've become chief engineer recently, but I had already been leading other developers for a while... but I keep writing lots of code, despite frequent interruptions to assist others... I can see how others often go in undesired directions if not guided back to focus on what is important. I am very glad my company has recognized that I can do that but knows me well enough to understand my strong point is coding, not managing. I am sure Apple and many other companies are also aware that a very experienced developer still writing code with others is worth a lot more than in some miserable (for them) management position.