Why does being able to point at someone else get people off the hook? The purpose of ritual sacrifice in society, is to publicly prove loyalty to whomever is the alpha (usually, some sort of organizational structure, but, interfacing human instincts like the alpha of a flock of Gorilla. ) Being able to publicly accuse and sacrifice an innocent person, is a way to signal "normality", or, loyalty. Submission. Ritual sacrifice is all about that. Sacrifice of children to Moloch 4000 years ago, proving you put the state above your loved ones, your own children, and then you are allowed to exist, welcomed by the cult.

Synapses

Watts, J., Sheehan, O., Atkinson, Q. et al. Ritual human sacrifice promoted and sustained the evolution of stratified societies. Nature 532, 228–231 (2016). https://doi.org/10.1038/nature17159