It's a big problem with kids editions of anything. Masterchef Jr. just ended and several of the kids on that show were cringeworthy.
Never watched it but I did see some ads for it and yeah... Very cringeworthy.
I did watch some episodes of Who Wants to be a Millionaire when they had a "Whiz Kid" week and they acted the same way.
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Wasn't there a story about Marc Summers losing his shit on some bratty kid on the set of Double Dare?
No, I think you may be mixing in different situations. Marc had to pull back a father from his kid on the Family version of the show because the father was mad that his kid messed up on the obstacle course (didn't win the grand prize -- a brand new car); The father grabbed his kid by their neck and held them up against a wall.
He also recieved messages from parents complaining about their sons/daughters messing up living rooms when making obstacle courses. Marc simply said, "It's not my fault... They are your kids. Take control of them." Marc said multiple times that the kids on the show were easier to deal with than the parents. He enjoyed doing the 2 vs. 2 kids seasons of Double Dare far more than the Family seasons.