What is the point of Landscape actor created when importing tiles in World Composition?

Hi, I would like to know the point of the Landscape actor created when we import tiles when using World Composition. When a tile is loaded, a LandscapeStreamingProxy object is instantiated in the level and the latter references the Landscape actor. On the other hand, LandscapeStreamingProxy has all the properties a Landscape actor has. I would tend to think the Landscape actor would define global properties while LandscapeStreamingProxy would enable to override them, but when I assign a material to the Landscape actor, it is not reflected in LandscapeStreamingProxy object (and the material is not applied to the actual tile). So this is a mystery to me, what is a point of this Landscape actor? It is really used/useful?