To me that creates the question why I would read the comments in the first place. Because "filter to the left" contains not one post that would interest me. It also doesn't give me a feeling on relevant discrepancies in opinion.

If I could filter I would love to filter out everybody in the "filter completely to the left" as well as the "completely to the right" spectrum and just have the ones in the middle. The ones on the left are insanely boring and conformist, and the ones on the complete right are really just idiots.