Rubrics are a great example of educational bullshit.  They have a value, no doubt, but that value is this: setting expectations for an assignment.  They give a shared language for talking about outcomes.  Many dumbasses think that this means they are fair, and that grading is fair, but they miss this important fact: rubrics are not impartial. 

When we pretend they are, we neglect the reason for needing them in the first place. We've all (probably) had it where we received a grade that was lower than what we expected.  When we inquired as to why, we were told we didn't meet the requirements. In our mind, we disagree.  While rubrics do give a shared language for this, a teacher that cannot communicate requirements clearly has some work to do.  

Proponents of rubrics as the ending point for equity miss the entire fucking point that a rubric is not impartial; it if filled out by a person that has just as much bias and agenda as someone that doesn't have a rubric.  Three of the least competent people I've met in education have said this exact phrase, "It's not me.  I just filled in the rubric."  

In some cases, a rubric becomes simply a legal way to fuck someone over.  

In my first year of teaching, I had a very advanced writing class.  I offered students the option of a rubric (impartial) or teacher based grading.  I warned, as I always do, that the rubric will be harder than I will be.  I'm a softy, so I err on generosity.  But I had rubrics at the ready, because, beyond a certain point, the debate of a grade is a stupid argument, and one I was unwilling to have.  If a student wanted, they could use the rubric.  The thing people forget is this: Teachers create the rubrics they use for a given assignment.  (If they don't - which is the case of the three Incompetents - the rubric is at best ineffective and worst unethical.)  This means they know the rubric when they grade.  A grade is often explained in the comments.  

The reason this is so is because they don't allow for trial and error.  I introduced the - and ( ) to the class, and one of the students really liked trying the use of ( )'s.  The thing he neglected was that (he used them for essential information).  Which made sentences read how I just wrote them.  This is errant use of the language, and could be considered at the bottom of the rubric's scale.  But if he tries and fails and then receives a failing grade, I essentially stifled his voice, which was the opposite of the class's intent.  Instead, I marked it a little bit down, encouraged his creativity, and taught the difference between essential and inessential information.  A win for both of us.  

When you're a teacher, you're making a judgement call anytime it comes to grades.  Unless the rubric is 'yes' or 'no', there is room for debate.  What's the difference between a 1 - 2 - or 3?  Depends on the teacher.  Some teacher's 3 is another teacher's 1.  It's all a judgement.  

So I'm not blaming rubrics.  I'm simply warning against anyone that suggests a rubric is impartial.  When we make this mistake, we can hurt people.