I would have appreciated more definitive comment on Frank's 'Americans,' possibly intentionally ambiguous? Also the who/what/where does/did photography go from "deliberately ambiguous."

John Singer Sargent's 'Daughters of Edward Darley Boit' comes to mind--amidst all that formalism is the very deliberate ambiguity Frank uses to such divergent effect years later.

I wanted to point out that there are three podcasts about Frank and the exhibit available at the first link in your post.