Every real pipeline has an orchestration layer whether or not anybody built one deliberately. If nobody did, it is a person with a mental checklist, and it stops working the week they are away.
What it has to handle is mostly unglamorous: ordering, retries with a limit, partial failure, and the escalation points where a human decision is required. Retries without a limit are how an unattended job spends a budget overnight.
Keep the orchestration deterministic even when the steps are agentic. A model choosing what to do inside a step is useful; a model choosing whether the step runs at all is a system nobody can predict or audit.
Should the orchestration layer itself be agentic?
No. Keep judgement inside steps and keep the control flow deterministic, or you get a system whose behaviour cannot be predicted, reproduced or audited.
What is the most common orchestration failure?
Unbounded retries. An unattended job that keeps trying is how a credit ceiling gets discovered the morning after it should have stopped something.