APIs that store state for a user between calls are more strategically valuable to their providers.

The useful data accumulates between calls, so that the value of a given API to a given user goes up the more they've used it in the past.

This creates an auto-catalyzing personal moat for that user.

APIs that don't store any state and are a fresh response each time are very easy to swap to a competitor.

This makes them more commoditized than they otherwise would be.

LLM models don't store any state, are highly commoditized, and are also insanely capital intensive to set up.

Not a great business!