I think culture is a big part of it and promoting the right people. Most companies when it becomes the size of apple are riddled with politics and the people on the top get there not because they create/design great products but know how to play the "game".

One thing that strikes me about apple is their culture of secrecy. There are departments within the same company that are not allowed to talk to one another. When you have no idea what other people are doing, it's very hard to play politics and the only thing you can do is just do great work.