We take care of the dead so the dead will take care of us.
We honor the dead so the dead will honor us.
That all cultures do it isn’t proof that it matters or that the dead have any influence, other than the memory of their existence.
War hasn’t ended might be proof that the dead are wanting us to war. Or maybe we’re misinterpreting the dead. Maybe the fact that we war is only proof that we want to war and we want our dead to be on our side so we can win that war.
Just in case, because we don’t really know, we might think to go the peace without exception route – this time, next time too.