In a private blockchain network, if there are three nodes - A, B, and C
A is connected to
B is connected to
But, why is
A not connected to
Wouldn't that make the connections and ultimately the network more reliable?
N nodes connected to all
N-1 others, that would require a lot of bandwidth and work managing all these connections. There is a whole field of research dedicated to optimal connections distribution given a desired "network diameter".
Not to forget that certain network topologies, think NAT and port-forwarding, do not allow all nodes to connect to each other.