Mostly because I don’t believe that left libertarianism is a real thing or at a minimum has zero practicality and so not a serious position. You can’t want the government to have a heavy regulatory hand but still want them to stay away out of your life and wallet. Those 2 thing’s don’t go together. So if you chop that quadrant off you get the 3 sides.

And it better shows the alignment of fundamental value of each side more clearly, at least to me. It shows how what we call the right is really split between 2 different core values that reduce the other as one increases. It’s the fundamental divide on the right.