I like the defense-offense metaphor you used here, it really drives your point home:
Eliminating your distractions is all about playing defense. If you don’t begin here, nothing else will really matter. All the “offense” in the world won’t matter, because you’ll compromise your efficiency by falling victim to distractions that take you away from the task at hand.
In terms of the first point, I actually mentioned the same thing (about the importance of eliminating distractions) to a friend of mine. She is an incredibly productive attorney, has written a number of books (ABA bestsellers), is always traveling around the world and has the most amazing personal network I have ever seen.
Anyway, she disagreed with me and said that distractions are helpful for her and that without Social Media, her book would have never been written. She apparently got inspiration for her book from her friends on Facebook and toggled back and forth between tasks.
I found this rather surprising but it made me think that perhaps the standard productivity advice is not always true for everyone.