I think we should dig a little bit deeper to find a thing worth resurrecting. What worked in FidoNet and earlier networks was the social organization, not protocols. A usual way to enter a net was to get a point level address from someone with a node. You had to know the person in the real world, and the person had to vouch for you. Your actions could have jeopardized the whole node, so there was a certain level of accountability.

I don't know to which level this element is resurrectable though. Why would one want accountability if there is internet where there is none?

The technological side is secondary. You can make an hierarchical network on mail protocols alone with a simple echo script.