We are here moving in a realm of ideas prevailing in ancient Israel respecting holiness, uncleanness and sin, which are ceremonial and not ethical; see especially Robertson Smith's Religion of the Semites, 2nd ed., p. 446 foll.
A milder form of penalty was the temporary separation or seclusion (niddah) prescribed for ceremonial uncleanness.
On the one hand, since that which is tabooed is held to punish the taboo-breaker by a sort of mystic infection, taboo comes to stand for uncleanness and sin.
By parity of reasoning a blood ritual may have been adopted by peoples who practise the expulsion of evils, conceiving them either animistically or as powers; catharsis, in the sense of removal of uncleanness, is not necessarily primitive.
In the sacrificial system of sin-offerings (Jhattath and'asham) we have to do with sin as ceremonial violation and neglect (frequently involuntary), or violation of holiness in the old sense of the term or as personal uncleanness (touching a corpse, eating unclean food, sexual impurity, &c.).