Why don't we use Real-time clocks and timestamps in Distributed Systems?

They're unreliable, because every clock ticks slightly different
Oscillating Crystals are used in an electric circuit for keeping track of time in computers
They oscillate quite stable but the frequency for each crystal is slightly different

In a distributed system with multiple machines, each clock will tick at a slightly different frequency

Gradually, the clocks of all machines will get out of sync (clock skew)

Diskussion