Message passing, it seems, is the basis for implementation of protocols, be it communication between objects in a hierarchy or between actors/processes in a system or nodes in a network.

It is not coincidence that message passing is the core concept in the original OO paradigm and in design of fault-tolerant distributed systems. Cells do message passing too.

I am not sure what is being copied here. Messages are just structured data (a molecule) in otherwise share-nothing architecture.