I'm not sure. We have distributed systems of this type at $JOB and a correlation ID that is generated on user action and attached to every event in the chain (regardless of service) is plenty. I don't think we've ever needed to look at anything so specifically that a unique event ID for each event would have been helpful.

You also get event IDs "for free" with lots of systems, e.g. Kafka topic/partition/offset is more than sufficient as a unique global ID for later use.