Yes, they stem from the human sacrifice of captives at the funerals of big guys, really old. Downright sacred, originally, not just a spectacle.

Your proposal sounds good. If I interpret it properly: cultures have old traditions that live on despite maybe even contradicting their own values. I.e. if they had to invent it at that, they would not, because it contradicts the values, but being a tradition, it carries on.

For example today we would not invent cars or at least would not allow civilian car ownership. We have a safety oriented culture and proposing that every chump should be allowed to drive two tons of steel with 180 km/h top speed and easily wiping out a bus stop full of people if he falls asleep or killing a whole family in another car, if it was proposed today it would be shot down as a CRAZY dangerous idea. It would be seen as far worse than civilian gun ownership because with a gun you don't kill five people by mistake. But as it is an old tradition, so lives on despite contradicting accepted values. But if we had to invent it now, we would be horrified.