Gender reveal parties aren't some ancient tradition. They're a few years old. They're part of the conservative backlash against the increased visibility and tolerance of trans people. They're not "just an excuse for more gifts". They're inherently oppressive and violent.

Gender reveal parties are an act of violence against trans people. They're performances meant to loudly declare one's side in the culture war, signals to any trans or gender-nonconforming people in those families that they better keep it to themselves.

You don't hold a gender-reveal party just to squeeze more gifts out of your friends and family. You do it to announce to your whole family, your whole community, "There are only two genders in THIS house!" That's why there's usually pyrotechnics. They're an act of intimidation.