Maybe its most useful to think of this as sort of an "isometric" 3D rendering, because this extra dimension is usually only exposed to the user modally: the third dimension is whatever site you happen to be visiting at the present time. By 2D I was mostly referring to the interface, which is a "matrix", and commenting on how that particular metaphor makes managing a complex request blocker a much better experience.

> It's actually 3 dimensions, as any selections you make in that UI only apply to the site you're currently visiting.

Well, technically that is only partially true as the third dimension is the (sub-) domain scope or "*" which can be reflected behind the scenes with the first-party settings for the origin's domain for each request type because it has the identical effect.