It’s definitely true sometimes. The tortured revolutionary that took it too far is a very common trope. A lot of the time, it’s just very wishy-washy, as you’d expect from a mass produced cash machine like Marvel. When you’re making so many stories, they’re not all going to be winners, for any number of reasons. The people that think Marvel is making propaganda are just looking for it. The movies just aren’t that good, they’re not hiding some sinister motive