Don't get me wrong, I think it's a great resource, but it's not "How to be a manager."
Just an example of this, culture is hard to get right. You can't hire yourself to culture. It's something that has to be practiced by all your employees every day.
If you have 1000 managers in your corporation, you have 1000 micro-cultures. If a chunk of those managers figure out they can berate their directs on a daily basis without punishment, then those employees experience of your company will be terrible.
That's why Amazon employee reports vary wildly from great to horrible. That's because while some managers are truly great, some are truly horrid. The culture isn't enforced equally across the company.
Jeff Bezos might treat his corporate execs great on a day to day basis say, but the average employee is usually levels of management removed from this to be inspired. Instead they see coworkers sobbing at their desk because they were fired, or forced to resign. Other's might actually deeply enjoy their time at Amazon, but it's because they got lucky in the micro-culture lottery.