... we're connecting people. That's what we're addressing, but it's also who (much of) the messages we're sending are consumed by.
On that layer of abstraction, instances are routers. Instances do form a mesh, more or less, so in a sense the fedi topology is very comparable to it's packet switching underlay, where instances are akin to edge routers that connect users in a star pattern to the mesh of the core fediverse.
Except.