I think Parra 47 is saying (and has said before) that there is a distinct difference between a half-back and a five-eight. And he's absolutely right about that.
Well that's obvious. One plays at first receiver while the other plays second receiver. The dispute was whether every team (or even every successful team) uses this structure in the modern game. The fact is that few teams play this way, and for good reason.
With Norman and Gutherson, Parramatta were playing with two five-eights. Now we have a half-back (Moses) and a five-eight (Norman). I think it's going to work well. Some teams operate with two half-backs, but we now have the more traditional model.
I mostly agree, however we actually have two players able to play both roles. This makes us extremely versatile and able to target the opposition's weaker side without losing the option to attack both. We do this by playing split halves.
Look at the Dragons game - we were able to heavily target Sims and McCrone without changing our shape. Norman got far more ball on the left (often from a midfield play the ball) than Moses did on the right. But both players like to get wider with some space. Middle forwards often catch-pass to either of them from first receiver.
They also share the kicking duties fairly evenly.
So yes there are more traditional halfback/five-eighth combinations in the NRL, e.g. Pearce/Keary, Sezer/Austin, Cronk/Munster, Green(halfback in jersey 6)/DCE(five-eighth in 7), we are not one of them. Though that might change as Moses settles into the team. It's worth noting that this more traditional shape is also used when one of the halves is makeshift (e.g. Gutherson).
But so far Moses/Norman (or Norman/Moses) have played in the modern split shape. If you think you've seen Moses at first receiver and Norman at second receiver it's because you have. But what you've not noticed (or blocked out from trauma) is Norman at first receiver and Moses at second receiver.