This isn't fundamental. The large-block miner can pre-stage copies of the block (before the nonce has been found) at a few replicas. If they successfully find

This isn't fundamental. The large-block miner can pre-stage copies of the block (before the nonce has been found) at a few replicas. If they successfully find a nonce, they blast the nonce to all of their replicas, which immediately disseminate the complete block.