[Yeah I thought Hindus generally avoid harming animals because of the reincarnation thingy.]
While in theory, you could sacrifice animals without eating them, meat has traditionally been pretty expensive, because to get one pound of meat requires several pounds of feed. All these sacrificed animals are eaten. If you think it through, given the longevity of these traditions, it’s doubtful that pre-modern peasants who typically led a marginal existence had the financial wherewithal to simply sacrifice animals and bury them.