For what it's worth, everyone could be sitting for the fireworks and it only takes that 1 person to try and jam in at the front and stand and it creates a chain reaction.
We (and another couple) got blasted at a
MNSSHP in 2014. We camped out for about 45 min to an hour before the first Boo to You parade. We were all sitting on the curb, because who's gonna stand for that long. Well, 2 things happened. 1 - it started to rain and 2 - the parade was about to start. So we all stood up, like everyone else around us. Well, this didn't sit well with the people behind us. We got blasted that we were rude and we were blocking the views of their kids and that we should let their whole family in front of us, etc.
Well, the girl in the other couple turned around, looked at the lady and said "we've been here for some time, there's other spots along the curb where you can park your stroller and watch the parade". We all looked at each other as this lady just kept going, and she actually tried ramming us with her stroller. That didn't go over well and we all stood strong and didn't give in. Eventually she gave in and went about 15 feet down and had a spot... until the CM's came through and promptly escorted them out because they didn't have party bands!