Yes that's true. There are no loops or gotos and functions have no side effects. PostScript has all of that. But I think it would have been sufficient to remove the possibility of global side effects to support out of order rendering of pages. A purely functional language without global state could've done the trick.
So I suspect there were other reasons as well for removing so many features. Maybe the complexity of interpreters. I don't know.
I had heard something that the main reason for creating PDF was that you couldn't render a single PS page without rendering all the ones preceding it.