The problem with rubrics, like letter and number grades, is that they are a one-size-fits-all form of assessment and they are subjective. Rubrics use words like, "seems," "little," "mostly," "adequate," "some" and "weak," to name a few.
Although narrative feedback, the method of assessment that should eliminate grades and rubrics, may use subjective words in some cases, the feedback is far more specific and individualized. If the feedback says, "Very well done overall," this will be followed up with a careful explanation of what was done well. Rubrics don't do this, so even students who meet the learning outcomes don't know how they did it, based on a rubric. Consequently, learning is lost.
For example, on a major project, a part of a rubric may say, "Work displays adequate attention to detail." This statement has virtually no meaning. I'm not sure what "displays" means in this context, and "adequate" is a completely inadequate word in virtually every case. Finally, vague statements like this do not explain what detail the teacher wants.
If providing meaningful narrative feedback, I would mention the detail specifically. If it's a science project on hurricanes, I might say or write something like:
"Your project only partially demonstrates that you understand hot towers, based on the lessons and models from class. You need to add two or more captions to your drawing, explaining how the towers power the hurricane. Please make the necessary changes and resubmit."Not only does this feedback specify what is missing, it asks the student to return to the work, make changes and resubmit.
Because a rubric is a one-size-fits-all tool, it does not meet the needs of each individual and, consequently, fails students.