I suppose in some respects it's a matter of perspective (no pun intended). The ordered triple $(x,y,w)$ is a point in a 3-dimensional projective space that is mapped (projected) to a 2-dimensional point in the Euclidean plane: $(x/w, y/w).$ Given that, $(x,y,1)$ would be point2-dimensional plane in that 3-dimensional space (or a specific point if $x$ and $y$ are fixed) that maps to the point $(x,y)$ in athe standard Euclidean 2-dimensional plane.