I don't agree with that at all.
On the left-wing, we have the following options: Welbeck, Kagawa, Nani, Januzaj, Young, Rooney.
Behind the striker, we have the following options: Rooney, Kagawa, Mata, Januzaj
On the right-wing, we have the following options: Mata, Januzaj, Nani, Valencia, Young, RvP
On top, we have the following options: RvP, Rooney, Welbeck, Hernandez
That's an absolutely outstanding selection, both in terms of the starting XI and the depth.
I think that such thinking - no offence by the way, it's not personal - is more damaging than Moyes right now. Rooney will not play on the left wing, RVP won't play on the right wing ( unless we're playing 4-3-3 but for that you'd need pacey striker-wingers, neither Rooney nor RVP fit into this description ). Nani, Young and Valencia, three unreliable wingers, former being constantly injured and it's just some people's sentiment that makes them believe that he'll 'come good' or so, Young speaks for itself and I'd probably leave Valencia here purely for his versality ( right wing, right back that is ) even though there are games where he's looking cringey with his inability to do anything with his broken left leg ( yesterday's game wasn't the one, he was good yesterday ).
I'd say that nobody here wants to see Rooney behind the striker ( RVP that is ), it's simply not working, their partnership is ugh this season. Hernandez seems to be gone, same applies for Nani even if somebody insisted on him staying here, Young should be gone. Kagawa, Mata, Januzaj, Valencia for the three spots behind the striker - that's how I see it. To utilise Welbeck the best, he should become our #9, he excels there, so it's three strikers of Rooney, RVP and Welbeck up front. Of course you can throw Danny on the wing because he's pacey and so on, but as said, I think we should stick him in the #9.
Januzaj, Kagawa and Mata all offer very similiar trait, they're not very fast ( Januzaj is easily the fastest out of those, but his speed is nowhere near Welbeck's or Valencia's for that matter ) and somebody made a good point, that front four of Januzaj, Kagawa, Mata, Rooney/RVP is possibly the slowest team you can get up front. We do need some winger that offers pace. I don't mind adding some youngster really, I'm all for it, but is there somebody who fills that role ?
I'd say that our depth - even though it looks good on the paper - is a bit glorified. Sure, compared to other formations it's Rolls Reus of our team but there's little versatility there. And I'd say that a year without CL is possibly the best year when you can fill in the gaps of your squad and build that depth.