Look at standardized testing in the USA (SAT, ACT) - there is tons of coaching and preparation specific to the test that isn't training anyone on the material. Instead, we know how much time to spend per question, how to quickly eliminate possible answers on a multiple choice to improve odds when guessing, what patterns in the language a question exist, etc.
I think this is so so similar to customer support and that issue big corporations (and especially us, as their customers, face) which is that quality evaluation is not something that can be boiled down to quantitative measurement. Sure, it can weed out many common problems, but it's just not worth it.
Judging workers solely based on some rubric will create a class of people who min-max the system and will lower the overall quality of the service provided, while disenfranchising the best employees.
On the other hand, maybe this will help move these opaque and (almost certainly) biased processes towards some better baseline.