It must know your business
Visitors ask about your prices, your opening hours and your refund policy. A general model cannot know those unless they are supplied and kept current, and it may guess when they are not.
It must do jobs, not only talk
A receptionist books, collects details and hands over. That needs tools connected to your calendar, your leads list and your team inbox.
It must follow your rules
You decide what it may offer, what it must never say, when a person takes over and which topics it declines. These rules should be enforced, not just suggested.
It must keep a record
Every conversation should be stored where your team can read it, search it and learn from it, with consent and privacy controls for visitors.
When a general AI chat is enough
For an internal tool, a demo or general knowledge, it can be fine. For a customer-facing website, the control and the connected jobs matter.