Originally Posted by Mulholland '49
Avengers wouldn't have worked out as well without the separate films.
1. Introducing each character: Avengers consists of 6 different characters from 6 VERY different universes. In the amount of 2.5 hours they would literally have to explain why there is a WW2 veteran transported into the future, a Green giant monster, a man in a robot suit, a Demi-god, a russian spy and Samuel L. Jackson in an eye patch are somehow connected in the same universe because you know... those things are kind of hard to understand out of context.
2. Back stories. Each one of these odd characters would have needed a back story. They would have to establish who Tony Stark is, his personality, his background. Bruce Banner's origin, his powers, why he is a fugitive. Cap's origin, why a man from the 40s is in the present, how did that happen, and etc. etc. etc.
3. Establish a main story. The plot has to connect each character in some way.
4. Threat. Have some kind of threat or threats. The villain, again has to be connected somehow to each of the characters, those character's back stories, their separate universes, etc.
5. Character development. Each of the characters in addition to showing their back stories have to grow as characters and go through some kind of arc together.
If Joss Whedon would be able to pull all that off in a 2.5 hour movie. Then he would be a god.
EDIT: It has nothing to do with how much each separate movie made in case that's what you think I was referring to.
But he did pull it off.
They established who Tony Stark is in the movie itself. The first scene he's in tells you he's rich, funny, "self-obsessed", etc. Stark talks to Banner about the thing in his chest that keeps him alive.
Stark being a former arms dealer, how he became Iron Man, etc don't feed into the story of Avengers at all, and thus the audience doesn't need to know about it. All they need to know about it, his powers and his personality, can be summed up in the dialogue, quite easily.
Same with Hulk. For audiences who are unaware (kids, especially), Hulk is explained in the scene between Coulson and Cap in the plane.
Cap is explained in the montage. That's why we have the montage. We don't need to watch The First Avenger to get Cap's personality. His personality comes through in his scenes in The Avengers.
Same with Thor. The first scene between him and Loki establishes their feud for the movie.
The tesseract is explained by Dr. Selvig in its first scene.
Again, people didn't watch the solo movies and were fine because the movie itself did its job and informed people of what they needed to understand the movie.
So yes, Joss Whedon did pull it off. He could have done it without the solo movies as well.
(it wouldn't have made as much money probably....but that's a different issue. And solo movies before the team up movie does make sense more than it doesn't. I'm just saying that it isn't necessary to make a good Avengers/JL movie)
And yes, the Xmen - Avengers/JL comparison doesn't make sense. In Xmen, they're all mutants. You wouldn't even need 'reminder' scenes of how they got their powers.