Descriptive Grading v Grading Based on Numbers

Why are grades always associated with a percentage? Can you truly demonstrate the difference between 89% and 90% of learning?
What if we attach descriptions to grades instead of numbers? Might that not be more helpful for students who are interested in learning?
If the focus is on how many numerator points students earn, then it's natural for them to ask to earn more points. But if the focus is a description of how well they've learned, then it becomes natural for students to focus on learning.
This document was made by Math teachers at Salem High School in Salem, VA and is a great starting point for how you could move away from point-based grading practices to more descriptive feedback that leads to learning.