, what you did this time around vs creating a new cluster and adding the hosts (basically importing the cluster) are not the same thing though - if you leave cluster on one host and then add it to a new cluster (or create a new one by enabling vSAN) then this is a new cluster with a new vsanDatastore and thus the issue.
In later builds (7.0 only IIRC, don't think was backported to 6.7) a guardrail has been implemented that will prevent adding hosts 2-4 to the cluster in this state with error message stating that the clusters UUIDs don't match (as they are basically 2 clusters).