My humble opinion on why is there so many writers and edition is because the writer interpret it in a way where you find it the most interesting and can easily transfer the information to you.

Just like how "Goal Settinig" books. There are so many authors out there talking about the same old thing. But the gist of it is the same. Only a few author you might think is the best because you can either relate to that book or the best way to make you understand.

My opinion is to spend some time on the bookstore to flip thru em.