I take it that theaters have changed in the past decade from flat floors to statdium seating so that the view is less likely to be obstructed. And the theaters are typically multiscreen. Thus if in fact you haven't been to a movie since Gone With the Wind, it's likely that that would be apparent to someone watching you find your way to a particular picture showing in a modern theater.
No, that would be acting like they'd been in a theater before. The claim was that they looked like they'd been in a theater before.
What we have here, IMO, is more of the author's bias that the religious crowd that made this movie a hit are a bunch of melons just out of the patch.