There is no such thing as "broader consensus". There is consensus and there is policy. There is no fuzzy line in between them. Both are part of node software and policy at least being somewhat common between nodes is good for the health of the network to reduce latency and p2p traffic, but there is no consensus mechanism involved and it is not crucial. You can run a full node without a mempool at all. Maybe you are referring to what might be called the "social consensus" within the broader community of node runners to adopt similar policy rules?