That was a product of a bubble of 1970s liberalism that was open minded towards sex between adults and young teenagers. It was an intersection of the 1960s sexual revolution, and the 1960s trend of treating kids more like adults (e.g. Tinker v. Des Moines)—but prior to the #MeToo era focus on affirmative consent and power dynamics. They simply couldn’t understand the backlash against Polanski.