That’s the closest I’ve been able to think about for why people turn to puritanical values in the first place: jealousy that others can do fun things they think they can’t, plus maybe a second layer of being upset that some aren’t also upset about it.

Oh wait, I almost forgot about the control angle, where if you can convince enough people that some normal and ok aspect about humanity is actually wrong, then you can catch people “slipping” and manipulate them via guilt or blackmail.