I took a shortcut when typing that, quoting the OP instead of further explaining. It is definitely possible to visualize 4 datapoints, but not 4 spatial dimensions. The only way to do so is to project to lower dimensions or take a lower dimension slice and display that. That works for 2D slices/projections of 3D objects because we already have a full understanding of 3D. It does not work for 2D projections of 4D objects, similar to how "flatlanders" couldn't make sense of a 2D or 1D projection of a 3D object.