Not sure why Elasticsearch is needed

We deployed OpenVidu Pro in AWS and everything is working fine, but we are still not sure why Elasticsearch and Kibana is needed for OpenVidu, how big our instance of OpenSearch should be and how many of them should be running. So, maybe someone could provide me more information for what purposes these services are used, because I struggle to find more information about this.

  • is it tragically bad to not use external Elasticsearch and Kibana in production?