That is what the authors stated means in practice, so your assessment is correct. This seems trivial, like I can just use an onion router for this.
That said, I agree, you could absolutely do the same with an onion router. This simply provides the benefit without having to do so.
As someone who uses tor everyday, you basically can't get any higher quality general purpose search than duckduckgo or searx to actually load over onion routing. If you position yourself in such a way that your results engine returns queries on par with those two (or preferably better) you will have a rock solid product in your hands.