_ x and _y aren't really encapsulated any more. Admittedly splitting hairs here, but yes they are encapsulated. They are exposed in a specific context/meaning/use. They are not exposed for general consumption - i.e. that getter we're avoiding.

RE: the variation of the visitor pattern.... Made me think about IEnumerable - it returns an enumerator object without exposing the object being iterated. SO, what if we have Corrdinate.GetPositionTransformer() - returning a PositionTransformer object with the coordinate state pre-injected. I expect the implementation can keep the UI decoupled.