Joel Selvin rock critic for the SF Chronicle wrote a scathing article about how those shows were run. He used the term “Push them around a bit” when it came to crowd control. It was bound to happen at some point.
Festival/general admission seating is still a thing. I usually don’t go up front unless I really like the band AND I’m certain it won’t get crazy. I did go to a metal show recently, and the surge was scary. It’s amazing more people haven’t been killed since then.