The commercial pull of a companion product is towards longer sessions, and the creator's interest is not always in the same direction. Leaving that tension to a wellbeing page is how it gets resolved in favour of whoever is paid per message.
So it is a boundary field. Conversational features are disabled unless explicitly licensed. A creator who enables them also sets a session cap, a rolling window and a variety nudge, and chooses whether the cap is a soft advisory or a hard refusal.
The default is a nudge rather than a block, because a hard stop the creator did not ask for is also a decision made on their behalf. What the platform does not do is leave the lever out of the interface and describe the tension as a value.