Use case:

A company might ask the firm that manages their company website to implement a WebRTC client to let visitors open audio/video communications with the sales or the technical department.
For example, a client might view a product on the website, and beside the picture find a button that says, "Click here to contact us." Upon clicking the button, the client will be able, through their own PC and without incurring additional data traffic costs, to contact customer support, which will answer their questions: "Is the product ready for delivery? Can I see it? Etc."