Note on Time, Clocks and the Ordering of Events in a Distributed System via Leslie Lamport

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.

FROM:

Leslie Lamport

Time, Clocks and the Ordering of Events in a Distributed System

Source

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.