Not always possible when escaping from a building in a normal situation. In a nightclub or confined outdoor concert situation, the situation is worsened because of the density of the crowd. I also recall an incident in Britain where the crowds had to escape a fire but a barrier fence impeded their ability to flee in the most natural direction - out on to the field. There have been several notable night club fires where the density in combination of restricted access to exits compounds the problem.

2ndly people tend to try to leave via the same exit they came in instead of a more immediate exit. 3rd people tend to want to find each other in a crowd so they can leave together, not knowing that they are simply compounding the problem by milling around, fighting the flow of the people and causing traffic blockages. And 4thly, what is worse is the lone person separating from his personal group to "go check things out, assess, and return".

People might be stupid in a normal situation but in a crowd they are absolute idiots.