why use the event emitter instead of the asynchronous function

[Sivaharish12]

Why the event emitter is used instead of the asynchronous function because the asynchronous function is also capable of doing the emitter so why do we use the event emitter.

[preveen-stack]

https://stackoverflow.com/questions/27677692/performance-cost-of-pubsub-excessive-events-and-event-handlers-in-javascript

Perhaps the above can shed some light