Not necesserily, it's still good to realize that there would be a more efficient solution. This applies in the real world too: you might be working out the best way to notify servers of an event through P2P, but it may be better to simply notify those servers in some broadcast pattern. (The idea of a mirror to notify all soldiers at once would be a broadcast pattern)

Networks do not have the same physics/geometry as the vacuum of space, latency cannot be assumed to be 0.

The reason why latency in a network can not be zero is the geometry of space. In the real universe the only possible zero-latency (macroscopic) connection is the one that travels 0 distance.