Clustering and S2S Sessions

So I’m implementing these methods:

RemoteSessionLocator.getIncomingServerSession

RemoteSessionLocator.getOutgoingServerSession

I’m wondering why a given node in the cluster would need to get another node’s Server-to-server connection - why not make its own connection to a remote server? I’d think this would be more efficient than routing all S2S traffic through a single node in a cluster.

Thanks.