Hybrid should be required

There are actually use cases for RSA and ECC only. They require enough less resources than PQ algorithms that it might matter. For systems with secrets that expire quickly, PQ protection may not be important, since as far as we know there aren't currently any PQ machines that can break currently used key sizes for RSA and ECC. The converse isn't true, as there is very litte extra relative cost to adding RSA or ECC to a PQ algorithm and there is significant safety added by doing so.