As high-level power (decision-making) keeps consolidating with the few(er), the potential bottlenecks of decision-making pile up. Even if the handful of guys in control of everything are all complete geniuses in their roles, they are still humans who need to sleep, eat, take a break, take a vacation, have lives outside of work etc. If those few have to make more and more of the decisions, the growth of Apple is capped at their respective maximum output because the multitudes of those below them have to stand by until they can get approval/rejection/feedback.
This kind of thing works at a small company where the owner tends to (need to) be involved in many details. However, it doesn't work well at rapidly growing BIG companies. The answer is always the same: delegate as much decision-making authority down to those capable of making good decisions. This Christie certainly sounds like he could be one of those people but now he'll exit and lots of decisions he could have made might have to be made by Ive.
Meanwhile, those who might not be as deeply experienced as Christie might grow more caution about making some proactive decisions without checking with "the boss" first (so they don't suffer the same fate). If so, it's easy to anticipate a scenario where you have thousands or tens of thousands of people standing by awaiting accept/reject/alternative feedback about what is probably minutiae-level decisions most of the time.
Senior leadership needs their time freed up to focus on "next big things," not consumed by minutiae or barely above minutiae-level details. Else, "next big things" keep waiting for their own attention while much more urgent (but relatively small stuff) get their attention now. Apple has grown so much so fast and yet the last few years have seemed to be about consolidating more and more of the decision-making with fewer and fewer executives. That doesn't sound good to me. But hopefully appearances are deceiving.