It's so tough to keep track of this series anymore.
So the fact of sealing Kaguya was to construct a moon around her? She's still there, just stuck inside those rocks in some alternate dimension? And Zetsu - the morphable, malleable, shadow-being - is also inside that moon? I am unclear on how exactly that amounts to defeating Kaguya. In a series where burying characters under humongous rocks does not guarantee their death even half of the time, how is this meant to convince us she's done for (let alone Zetsu, who can travel through solid earth anyway)? Her being in a separate dimension is also not exactly comforting given that she was the one who originally created and/or traveled to that dimension.
Is Kaguya supposed to be like Shedinja, where you can throw all kinds of powerful moves at her and they'll just bluntly fail, but once you make contact with the one particular thing she's susceptible to she goes down like a wet paper towel?
And I'm confused about that rabbit beast, too. It came out of her body (and apparently spit Madara from its mouth like a popcorn kernel) looking just like the other tailed beasts, who all took on their physical forms. So are we to assume it took a form like the others? Or do we assume it alone simply evaporated into nothing?
Then Hagoromo used a summoning jutsu to bring all the previous Kage back from "the pure land" - this series' afterlife? Forget for a moment my understanding that summoning jutsu require some sort of contract or marking applied to the summoned beforehand, but apparently now souls can be brought back from the afterlife? I'm also wondering why, if this Hagoromo guy has still existed all this time and still has these miraculous death-defying and interdimensional powers - including the chakras needed to seal Kaguya - then why ... has this whole series happened? Couldn't he do a single thing about the events of the world?
As far as Sakura goes, I think the problem is that we don't know how to properly value her kind of power. With characters like Naruto and Sasuke, we can see them training and can see them getting stronger because their powers are essentially about physical action. They are offensive characters who grow by defeating others. Sakura is a character whose skill set is defensive: she is a strategist, a healer, a supporter. It is harder to see explicit defensive growth. Take her forehead chakra thingy, the 100 Healings. How does she train for that? By concentrating chakra on a single focal point - essentially, by thinking. Physically, visually, there is no representation of that, except perhaps to show her with closed eyes and a slightly furrowed brow. And her healing powers must be shown to improve by the relatively vague measures of how long she can do it, how bad an injury she can do it on, how many people she can heal simultaneously, and so on. Defensive power will always appear weaker than offensive power by its very nature, but that doesn't mean it's not just as skillful or great.
I think we are justified in being generous when we compare Sakura to the rest of Team 7. One thing we all should agree on is that the author's execution in showing/explaining/proving Sakura's strength has been poor. Maybe he doesn't know how to show defensive power in a way that satisfied him and so didn't even try, or maybe he really is just terrible at writing for female characters. Either way, Sakura's story has not been written as well as Naruto's or Sasuke's. Yet at the same time, we should all agree that the author's intent has been made clear: we are supposed to understand that Sakura is presently an equally great member of Team 7, or that she is as close to Naruto's/Sasuke's equal as anyone could get. As I say above, proofs of this are thin on the ground, sure, but I think that's a fair reason for us to make the most of those that do exist.
Take Sakura's head-punch to Kaguya. Sure, it was simple compared to what the other two were doing, but maybe we shouldn't think that just anyone else could have done it. Maybe that punch only worked because of Sakura's Tsunade-style strength. We've seen Kaguya shrug off some good blows, and we also agree to regard her as the yet-strongest villain, so it is reasonable to think only Kage-level strength could knock her back. We know that Tsunade is physically stronger than the Raikage, and we know that Sakura is as physically strong as Tsunade; therefore, Sakura is physically stronger than the Raikage, which is an impressive feat for a regular old teenager (and, given this manga, a female one to boot). (Perhaps someone who can quote chapters can tell us whether there is reason to think Sakura is even stronger than Tsunade.)
In regards to her medical ninjutsu: We know that Tsunade was regarded as the best medical ninja in history, and we know that the most obvious symbols of her strength as a medical ninja were her 100 Healings jutsu and her ability to distance-heal through the Katsuyu summon (which works off the summoner's power, not Katsuyu's). Now we know that Sakura can summon Katsuyu and distance heal as well, and we also know that Sakura has surpassed Tsunade's 100 Healings, e.g. that she could do it earlier/faster than Tsunade (and that she can use it to more effect since she does not have to apportion some of it to make herself look younger). So we would be justified in thinking that Sakura is now the best medical ninja in the series.
I've tried to give the best case for Sakura's greatness. The point is to persuade others that Sakura deserves for us to consider her as great as we consider Naruto and Sasuke (despite the fact that the author has done less work to convince us so). And - crucially - that we need not consider her great in exactly the same way. You could figure out who is the world's greatest biologist, and you could figure out who is the world's greatest physicist, but you would not be able to determine which is greater than the other, for although each is doing science, they are doing it in different ways and with different tools and produce different contributions to knowledge.