Running an instance is pretty trivial from a sysadmin standpoint, so I do lean towards smaller entities just running their own, to prevent monolithic censorship.
They can just disable comments so they don’t have to moderate anything. A county could run just a read-only instance that would have a community for every department that needed to do public communication. The road department could post about a bridge closure, the conservation district could promote a volunteer event, and so forth.
A series of tubes, you say?
I used to haunt surplus yards as a high schooler in the 1980’s. There were a lot of pneumatic tube components to be found as the world was switching to electronic networking. Pumps, boxes of o-ring seals, tubes and junction fittings.