something I might add to this fine list of reasons is a simple idea of the loop tools in Blender…
in order for the loop tools (edge loops or face loops) to work correctly quads are needed…
if geometry is a triangle or an ngon there is no direction of North, South, East, West…
without this direction the loop tools come to an end (terminate) because there is no continuing without knowing which way to go…
this is important especially to box modeling when you want to be able to add loop cuts and not end up with spiralling loops or loops terminating in some odd place…
