Oh, sure, anyone can just run down the street like a jackass pushing everyone out of their way. But then someone might just push back. But if you run down the street shoving people aside while invisible, people will assume you're a ghost and clear a path for you, by running out into traffic if necessary.
Which, apparently, was also the reasoning they used in the first Fantastic Four movie, where "only" invisible Sue could push her way through a crowd. (She did so by pushing people. While invisible.) Of course, Movie!Sue had to get naked in order to become invisible. And apparently if you're invisible and naked, there's now crowd on Earth who could possibly block your way.