Does he give concrete examples of where this happened? I don't have an account so can't see the rest of the replies.
I think this is too simple an explanation. This is more a single data point in a collection of issues for why civs fall. For example, "sexual debauchery" is not necessarily the driver of collapse but it does contribute to reactionary responses that leads to revolutions which can lead to declines. The other side of the same coin is that this is also a sign of lack of "order" in a society overall and one of many signs of a declining civ as again.
I prefer this explanation that I think is more general and encompassing instead of a singular cause.