I know someone who was banned for five years. Big Chester City fan. Rarely missed a home match. He got into a scuffle, with a steward, and he absolutely to this day swears it was not his fault (he says he was just going to help another fan who had got into an altercation with said steward, and he started on him. He's adamant that no punches were thrown). Five years. He's a big fella, but a good lad, and I completely believe him. He's still bitter, and pretty much stopped going regularly after that.
By comparison, I'd say that what those people did was much more serious, in terms of putting the club at risk for a heavy fine, or worse, like points docked at the start of next season. It infuriated virtually the entire stadium, including players, manager, backroom staff etc.