Without this, you lack trust in test results, and it is not possible to isolate the source of problems or prove problems are resolved prior to deployment.
Without this, it is not possible to accurately predict real-world performance, and you lack confidence that what you see in the lab will translate to a real-world deployment.
Without precision control of delay, packet delay variation (jitter), and impairment conditions you lose visibility into issues, and can not quickly resolve performance or functional issues.
