RIDs can overlap, masking one node's replication progress and failing to correctly report write concern (under counting the number of nodes who have received the write).

RIDs can be replaced when not entirely necessary. If a node changes its hostname, it will choose a new RID. This can result in its replication progress being reported to the primary as two different nodes, resulting in falsely satisfied write concerns.

Current proposal: use a combination of config version and _id from that config to uniquely identify nodes instead