This shouldn't come as a surprise. They are the cultural descendants of those 17th century Massachusetts puritans who were also sex-obsessed and intolerant.
The Leftists would be burning witches--i.e. those who interfere with their agenda or disagree with their dogma--right now if they could get away with it.
They would love to pass laws making everyone keep the curtains at their windows open at all times so that the morality-police could look inside and see what they're up to--both literally and metaphorically.
You are wrong about the Puritans — they had a healthy view of sex, actually. But they did not write the histories you’ve read — the enemies of sanity did.