Why didn’t sending metrics or traces create a dataset?
Datasets and collections are for logs only. OpenTelemetry metrics sent to/v1/metrics appear in the Metric Explorer, and traces sent to /v1/traces appear in Explore Traces. They do not create or appear in datasets or collections, even when the request includes x-bronto-dataset or x-bronto-collection.
service.name and service.namespace still provide useful service identity on metrics and traces, but their Dataset and Collection mapping applies only to log records.

