Wizard of Oz as a Populist allegory

Was The Wizard of Oz indeed a Populist allegory? This year we viewed clips from it in our American History Advanced Placement class and were informed of the alleged allegories within, but tomndebb made a passing mention to this as an apparent myth in a recent thread.

What’s the Straight Dope?

The Straight Dope has touched on this a time or two:

Beginning with the Master’s comments (including a link to a debunking).

Continuing through one protracted discussion (with citations and everything).

And ending up as satirical commentary.

Oh, and this short thread includes a reference to the author of the “populist” theory admitting that he made up the theory and that Baum had no populist leanings.