That is what happens with all parallel views. In a plan view all verticals have been foreshortened to zero. Everything that is not parallel to the picture plane is distorted in projection. The idea of the isometric view is that all the lengths along the three orthogonal axes are distorted equally.
As I wrote earlier, to me it seems that the only thing these non-orthogonal parallel projection views are used today is as assignments to beginning architecture and engineering students. When everything is done with computers they are otherwise obsolete.