I totally agree with you @Flerken but the answer for all those "whys" is if not, there wouldn't be so many movies and Endgame wouldn't have last 3 hours and, then Mavel Studios wouldn't win so much money. 

Yep I know, LOL

FlerkinGherkin, the Orb wasn’t destroyed. The Tesseract was destroyed but the Orb was not.

Unless the Avengers had a device lying around the compound that could unlock the orb, then they probably opened it by force. We don't know because that's never shown. Even if they were able to unlock it, there's still the tesseract and the scepter that were broken

About one year ago, people were saying something like: Tony can't build the Infinity Gauntlet, it's not science, you need Dwarves and magic, blablabla. Then it turned out Tony could do it. How difficult could it be to make other stuffs, with enough people make sure what their originals look like?

In reality, the only thing you need, to avoid the dark splinter realities, is to bring the stones back to their timelines. In reality, it doesn't matter how, because you just want the stones to do their job so that the universe doesn't fall apart. So you don't really need to place the space stone in the Tesseract, the mind stone in the scepter, the reality stone in Jane Foster and the power stone in the orb. You could, theoretically, put them in the ground. The timelines have already been changed. When you time-travel to the past it creates an alternate timeline. But if you take one stone from that universe, it will fall apart, so you need to place it back to the same time it was removed. Obviously this comes with a small problem, the power stone, because when it was removed from that universe, we see War Machine leaving with it, and Nebula is left behind struggling with the network it shares with the other Nebula. At this point in time, Cap would be with the power stone. So while Nebula is captured and Thanos is taking care of all of his time-travelling plans, Cap is somewhere around Morag placing the power stone on this universe. Meaning, that Cap didn't needed to spawn in the exact same place where War Machine left that universe, indicating it doesn't need to place the stone back to the orb or back to the same place. The events will go on in different ways. That is evident, as he returned to Peggy Carter without removing any stones, and the timeline went in a different direction nevertheless. The original universe, in which Thanos destroys the stones, isn't transformed into a dark reality, because the energy of these stones didn't disappear, instead dissipated itself across the universe, meaning that the stones still exist and protect the universe from other realities, but not in the form of solid stones. After all the stones were, early in the history of the universe, manufactured by ancient beings, meaning this is not their original state.

You know a movie is good when HISHE makes 3 videos about it. 4 if you add Endgame teaser HISHE.

Good point Miguel, except you can't just put the power stone on the ground or it'll destroy the planet. The only reason they'd need to put them back in their containers is so they wouldn't cause any more unnecessary alterations to the timelines, as their goal in the first place was to change as few things as possible.

Going back in the past creates an alternate timeline, but if you go back to a moment in one of those alternate timeline, shouldn't that create another alternate timeline? Meaning there'd be no way to put the stones back in the original branch timelines.

It seems going back to an alternate timeline you visited somehow doesn't change the outcome of that timeline. I mean, in the power stone timeline, we have seven major events that involve time travel, and, supposedly in chronological order, would be:

1. Nebula, War Machine, Hawkeye and Black Widow time travel to retrieve the Power and Soul stones

2. War Machine leaves with the Power Stone

3. Hawkeye leaves with the Soul Stone

4. Cap time travels to return the power and soul stones (the power stone is likely back in the orb)

5. Cap leaves the timeline

6. 2014 Nebula leaves this timeline

7. 2014 Thanos and his army, alongside 2014 Gamora and 2023 Nebula leave the timeline

I would assume, that the mere fact 1. happened, the events of 2. and 3. happen, but don't change the timeline they are in. However, Thanos from 2014 time-travelled to the alternate timeline in 2023, and then he died there, and so Cap, when time-travelling to the same timeline before Thanos retrieved the Power Stone, should know the events that would happen after, meaning he could make things different. Because Cap needs to time travel at the exact time both stones were retrieved, and because that was before Thanos time-travels, what does that mean?

1. No matter what Cap does, the events that happen after (Thanos time-travelling) will happen nevertheless. This creates a paradox, because the reason behind Thanos time-travel was due to Cap retrieving the Power Stone and the Soul Stone back into that timeline, so that the universe wasn't ripped apart while Thanos and his army was working a way to time-travel to the alternate 2023. And this means that it was because Thanos time-travelled that the events in which the Avengers win, will happen differently, and Cap goes with the stones, and time-travels before Thanos time-travels in the alternate 2014. Which means, Cap returning the stones happened both before and after Thanos time-travels to 2023 (which is a paradox, and that's why it doesn't make sense).

2. When Cap time-travels to another reality, that reality will split as well. Because Cap knows what is going to happen in the future of the timeline he visited (Thanos is going to time travel), he change future events, and that's not how time-travel works. The reality is that, when he time-travels, a new alternate timeline is made, one where he appears, while the other is where he never came to that timeline. So, if he goes back to the timelines to retrieve the stones there is always another timeline where the stones were never delivered. Meaning there is always a universe that will be destroyed. Its dark, and brutal, but unfortunetly, eliminates the paradox. With the exception that, for that to happen, the timelines in which the Avengers are trying to retrieve more than one stone (2012 and 2014), there was a Cap from another timeline that retrieved one of the stones in time for the Avengers that were still doing the Time Heist to get another stone and go back to their timeline and conclude the Time Heist. Meaning another paradox, because the only way for the Avengers to get all the stones before the universe is ripped apart (event 1), can only happen if one of the stones is retrieved (event 2). Meaning that event 1 can only happen after event 2, and event 2 can only happen after event 1... which is a paradox.

In conclusion, time-travel in Avengers: Endgame doesn't make sense (I thought it did, actually, when I saw the movie firstly)...

The last sentence sums everything up. Really, time travel never makes sense.