I was listening to "Gilbert Gottfried's Amazing Colossal Podcast" and his guest was Robert Wuhl. Robert was a contestant on "The Dating Game" four times and they briefly touched on how many actors were contestants before they hit it big, and if you ever watched a "Before They Were Stars" special, you've probably noticed that a bunch of the game show clips were "Dating Game."
So here's why. Chuck Barris figured out very early that "The Dating Game" is only interesting if the three bachelors were lightning quick on their feet, so as an enticement to get trained actors on the show, he agreed to pay AFTRA scale for any union members who appeared as contestants. Not-yet-famous actors were contestants because, win or lose, they got their rent paid. If they were REALLY good, Chuck would even encourage them to return to the show under assumed names.