Routing is often mistaken for “pick the best model”. It is closer to choosing the right path for the work.
A path might include a smaller model, a frontier model, a private deployment, retrieval, a human review step, a policy check, an evidence check or a blocked state. The route is the combination, not a single vendor SKU.
The routing layer is where sensitivity, output use, budget and firm policy meet. It should be explicit enough that legal, risk and engineering can inspect the same rules.
If firms do not own that layer, it still exists, but it is implicit, fragmented across prompts and shadow workflows. That is a governance gap, not a speed gain.