All of these conversational AIs should either confidently detect a users intent or apologize and offer to forward call to a real person.

LLMs perform pretty poorly when you start try to restrict them too much (e.g. detect intents and control responses based on intent detection), the replies gets disjointed and weird feeling. An open ended prompt and chat completion gives a much better feeling most of the time but can go off the rails.

If you don't let LLMs handle the conversation entirely you get into insanely complex traditional engineering problem: (if user is complaining do x, if user asks a relevant question do y, if user asks an irrelevant question do z), which is an endless can of worms.