When configuring a cluster, some commands can be executed on any mongod, others only on a primary mongod, and others only on a mongos. All of these separate endpoints make the overall task much more complicated than it should be. It would be much better if we could connect one time and issue all of the commands we need to. Ideally, mongos would be this interface, because we have to provision and manage these nodes anyway, and mongos's job is already to dispatch commands to other nodes as appropriate.