A distributed system can be described as a particular sequential state machine that is implemented with a network of processors. The ability to totally order the input requests leads immediately to an algorithm to implement an arbitrary state machine by a network of processors, and hence to implement any distributed system.
Leslie LamportTime, Clocks and the Ordering of Events in a Distributed System
If you can reliably order events you can build a state machine. Otherwise, much of the system is spent communicating to agree on what is happening.
Josh Beckman