Ah, the primary use-case here is for developers to test microservices as changes are made to them - so one would typically be running this setup in pre-production / staging only and no prod user data would be involved. I would think of it as a way to run integration / e2e tests for each commit or pull request. Running these tests in the high fidelity test environment constructed this way reduces the bottlenecks on staging environments, and bugs are discovered / addressed sooner.