Because Cap was clearly in the right in this conflict, and they went out of their way to show it. And the movie was more about him and Bucky than anything else.
Lol no. He wasnt in the right. He broke up the Avengers all because some dead girl he wanted to boink said you should stand your ground. That certainly doesn't outweigh what happened in Avengers 4 and they could've had a much better response if Cap didn't fuck up.
I mean, Tony broke up the Avengers because his incessant need to control everything nearly destroyed the world in the 2nd Avengers movie, and his response was "We need to be able to be in control of everything now even more"
At least its better than the comics, where Tony Becomes Space-Hitler and opens up interdimensional space gulags and Cap just acts like an incessant child the entire time, and really only ends when the non-super people tell them to ****ing grow up a bit.