Extension of secrecy
With managers and executives it's not the inability to communicate, but a lack in willingness to communicate. Unless you have some mental/physical inability that prevents you from actually speaking and forming sentences, everyone can communicate with everyone else. And putting that aside, verbal communication is only such a very tiny part of what we communicate. Usually you'll be able to figure out what's going on without verbal confirmation. Managers won't last long if all forms of communication are missing though.
Also hiding behind emails not picking up the phone don't have anything to do with ineffective or proper communication. Setting aside that it may be rude. Not communicating in itself is a pretty strong form of communicating. It can mean alot of things "I don't have time," "I don't care (about you)," "I don't feel the need to talk to you right now."
And YES being able to effectively communicate what you MEAN to say is something that a good manager should be able to do. But it's difficult to say what is actually 'effective' and 'proper.'
