The only reason they need to be monoclonal is for drug safety regulations. It's easier to estimate efficacy with a drug of known composition, and safety is much

The only reason they need to be monoclonal is for drug safety regulations. It's easier to estimate efficacy with a drug of known composition, and safety is much easier too because immune responses to different proteins are tricky to predict. With a polyclonal, manufacturers would need to prove safety on every single antibody and guarantee composition of the mixture.