"When you are deciding what to leave out, begin with the author. If you see yourself prancing around between subject and reader, get lost." —John McPhee
Rather than personal experiences, I believe this quote is talking about ego. "Look what I know!" "Look how beautifully I string words together!" No matter how wonderful you are, when you take the reader out of the story they're enjoying, you've messed up as a writer.
I know about this because I have a tendency to employ purple prose. While I think it's dramatic and literary, readers just want a good story. Thank goodness I have friends and editors who don't let me get away with it.
It's all better with friends.