This topic is quite interesting.
On the one hand I do agree that there is a major safety concern in taking any form of firework into a crowded football stadium. Anyone who does so should rightfully be banned.
At the same time, I took a photograph in the late 1990s of the United team, young mascots included, walking out onto the pitch surrounded by fireworks - see below. One false move from one of those fireworks and Jim Dick could have been left claiming incapacity benefits!
Maybe Health and Safety didn't exist when we were in the Dr Martens League?