The points are very true and very well made
My weakness as a young manager was probably his point 4. I remembered how disruptive and annoying disruptions are when you are trying to get things done, so I often avoided using the phone or just walk over and ask to not interrupt the team members.
A good concept but as a result I used email far too much.
You need to watch the interruptions you cause carefully, but all/in/email is bad for communication.