I get where you're coming from, all the categories are pretty messy.
But I really think the "left" axis is about egalitarianism. This is how I see it:
- Far-right actively works to preserve and support structures of social hierarchy. Egalitarianism negative.
- Libertarians actively work to destroy some structures of social hierarchy but support others. Egalitarianism negative.
- Anarchist actively works to destroy all structures of social hierarchy, but are agnostic towards natural emerging hierarchies. Egalitarianism neutral.
- Far-left actively works to employ new structures that dissolve all forms of social hierarchy. Egalitarianism is a positive.
Obviously, nobody fits perfectly in any of these, and there are all sorts of overlap, and people who lie about their true motives and direction.
I don't see Libertarians on the left end of the spectrum, because they don't believe that egalitarianism is really a primary goal.
I guess the difference, is if you chart this, do you see zero as your center or zero as the far left corner of your graph.
I see Anarchist as a zero value and see Leftists as a non-zero negative value.