Actually we need local and universal time. Say you have a meeting with remote participants. You want to know that it's at 9am UTC. With only that everyone know

Actually we need local and universal time. Say you have a meeting with remote participants. You want to know that it's at 9am UTC. With only that everyone knows when to meet. You also want to know that it's at 4am local time. That way you know that you will be asleep. Universal time is useful for communicating. Local time is good for understanding whether people are likely working, eating, or sleeping.