Responses are not free-for-all comments
Ev Williams

Is there a way for me as a reader to opt out of this sort of filtering, or at least a way for me to see a list of all responses, regardless of whether the author recommended them? (Is that what the button at the bottom of the responses list does?)

Yes, I understand that this system is highly effective at keeping out trolls and spam, but as a reader one of the main reasons I visit the “responses” section of any article is to get the other side of the story; to hear from the people who may not fully agree with the ideas expressed by the article’s original author. When the visibility of such comments is entirely at the mercy of the one who wrote the article they’re criticizing, it’s very hard for me to trust that the responses I see are an accurate reflection of what other readers actually think about the article in question, and not just part of the article author’s personal echo-chamber.