Consensus is not about validity, it's about equality of data, which may be invalid and/or unordered. Although later you admit the need for a partial order to resolve conflicts, it's not clear what exactly you mean. There you can see how some projects aim to leverage a total order of potentially invalid data to get higher programmability & scalability: https://bitcointalk.org/index.php?topic=5478975.0 Anyway, a node itself is not a resource of consensus, which has to be based off of something unforgeable. We had an entertaining thread about this recently: https://bitcointalk.org/index.php?topic=5478152.0