Three points in support of the original post:
1) There’s a difference between kids inventing a game on their own and adults imposing one on them. Some posts here are confusing the two. If a bunch of girls invent a wedding game from their own imagination then we can call it harmless. This is different. Here it’s not just kids having fun. It’s adults designing the fun and putting a stamp of approval on it.
2) Some of the posts seem to operate from the presumption that it doesn’t matter much what happens when children are small. This might stem in part from our getting distracted by their cuteness. I am reminded of the foolish people who dress up little girls in clothing that is provocative on adults and ignore the harm they are doing because the kids look so cute. However, you can argue that little things matter more when the kids are small.
3) What makes this worse is that they had a little boy watching the girls. It wouldn’t be as bad if only girls were involved.