See openHAB 3.0 my getting started notes: Model and Pages for an example. tl;dr it gives HABot the context it needs to interact with it using natural language and it gives the Main UI the information necessary to construct Pages automatically for you so there really isn’t any need to create a sitemap unless you want to. When you have a model, the UI all but constructs itself.
I wasn’t aware that any bindings use the model. I thought bindings couldn’t see Items and therefore it shouldn’t even be aware of the model since it’s all done through Group membership and Item tags.
You don’t have to use the model. But I’ve been playing with it and IMHO it’s totally worth the effort. The way it builds Pages really makes it powerful.