I have a lot of issues with the list starting with its premise. I am curious if you think of this song first as a song of the musical theatre or as a very good song that happened to have originated in a musical.
I am not a big fan of "best" anything, at least not unless we define what we mean very carefully. To me, the quintessential element of a best musical theatre song is how effective it is in place. In this case, I plead ignorance, although I would not be surprised if you can speak to that. :-)