It's like what Aristotle said about the differences between the Rash, the Courageous, and the Cowardly.

The Rash person thinks the courageous man is too cowardly, and the cowardly person thinks the courageous one is too rash. So everyone will declare that they the others are extreme, and in so doing they build their biases in.

This is the problem with unqualified statements about who's to the left of who, and especially the problem with both-sidesism. The act of making that kind of statement doesn't happen in some platonic realm of innocent and honest self-reflection, and is every bit as poisoned by politicization as every other political activity.

It doesn't mean there's no truth or you can't say stuff like this, but it does mean that we're all within our rights to dismiss you as a bullshit artist if you don't show your work.