The claim that you determine the quality of comments without regard to the positions they express

...is not one I've made. Caring about quality of comments doesn't require having perfect perception of this quality that is unaffected by other things. But I'm quite confident in my judgment of the quality of the comments that started this conversation.

The vast majority of comments and posts are neither formal nor rigorous enough for their reasoning, when considered solely on the comments' own merits, to hold up to any serious scrutiny

They should be amenable to steel-manning, not impossible to criticize (though this is not what I was talking about).