"Progressives" (leftists) and diversity

True to form, newbie Congresswoman Ocasio-Cortez homes right in on the racial makeup of CBS News' 2020 election coverage team.  It also seems true to form for a higher-"ed"-infused perspective on diversity.  While there is clear focus and emphasis from both the campuses and from AOC on diversity of race, gender, etc., what about ideological diversity?  The conservatives are really keen on homing right in on the lack of that in the universities and in (non-Fox) 'mainstream media.'  What the "progressives" don't focus and home right in on, says as much as what they do harangue everyone about from their superior moral perches.  (AOC is apparently aiming to be the most obnoxiously zealous in such haranguing.)  She asks in a follow-up tweet, "Do you understand how fundamental the black experience is to American politics?"  Do AOC and her ilk understand how fundamental the conservative and/or libertarian experience is to American politics?

With honorable exceptions such as Haidt [edit: I had been under the impression Haidt identified as a left-leaning liberal, but he identifies as "a non-partisan centrist"], what an overwhelming portion of the Left side of the American political spectrum means by "diversity" is not what the rest of the country means by that term.  If anything, given the demographics involved, their push for greater "diversity" (their meaning) ensures more and more left-of-center opinion to the exclusion of the rest, and that doesn't seem to bother them much.

How much viewpoint diversity, exactly, is there in Ocasio-Cortez's congressional district, which has been touted for being ethnically diverse?

Classical liberal icon John Stuart Mill expresses a genuinely progressive sentiment as follows:

“He who knows only his own side of the case knows little of that. His reasons may be good, and no one may have been able to refute them. But if he is equally unable to refute the reasons on the opposite side, if he does not so much as know what they are, he has no ground for preferring either opinion... Nor is it enough that he should hear the opinions of adversaries from his own teachers, presented as they state them, and accompanied by what they offer as refutations. He must be able to hear them from persons who actually believe them...he must know them in their most plausible and persuasive form.”

This sentiment is reproduced by Daniel Dennett's reviving of Rapoport Rules for intellectual engagement and criticism.  It is the heart of a method of philosophical inquiry known as dialectic.

How can those claiming to be progressive be so oblivious?