Each visitor gets a unique URL for their conversation with you across time, with all messages, voice & video calls, and appointments in one place. It's one permanent address per 2-person conversation, rather than one address per person (phone/email) which is the root of most of our communication problems.
I guess it's more precise to say if anyone else is paying any of the cost, you're not really the customer. You're right that there are situations where the consumer pays (say, for a smartphone) and companies pay to have bloatware installed that tries to manipulate and monetize the device owner.