Though I don't really agree with the conclusion of this thread, it's premise is quite important.
When our only striker Martial was out, we struggled for goals. As soon as he came back, we got a lot better, hence the creation of this thread. Now that Rashford, our only decent winger is out, we are struggling. I'm sure once he comes back we'll improve, and then maybe another thread might be created for him.
And we can extend it even further. Let's say Pogba comes back to replace the worst out of Matic, Pereira, Lingard, etc. Then our midfield play improves and then we can create a Pogba thread. Let's say we finally get a RW on the level of our two other attackers. All of a sudden our attack is looking much better, and we might see another thread outlining his importance. Ditto for our DM and, until very recently, AM positions.
All this to say that we don't have a complete team. Having to play youth LB Brandon Williams and recent Championship acquisition Dan James on the wings against Chelsea isn't good enough for us. Having to play either Jesse Lingard or Andreas Pereira to supply our forwards for most of the season isn't good enough for us. Having to rely on players like Mata and Matic, even though they have performed as well as they can, is just not good enough.
The more we replace these sorts of players in our team, the more we'll see improvements and then hopefully "most important player" threads. Fred has been a good start. Hopefully we can address the RW issue that we've ignored for a few years now, and build on that.