It’s just difficult to describe, so instead of “click on the three horizontal lines thing” it’s easier to say “hit the hamburger” and the name stuck. I guess if they were going to just have an abstract meaningless icon they should have picked something easier to describe over the phone, for example.
It was, it's a simplified version of the original that included the border around the lines, similar to one of the examples in the article (imagine a physical restaurant menu). Along the same lines, the three lines have since been further simplified into three dots in a lot of places - no longer looking hamburger-like.
