"...Lack of coder personality" That's more that just a mere gripe.
Many a job has been won or lost based on the character of a prospect. In fact, I've lost count of how many times I've seen otherwise very technically skilled people lose out to basic inter-personal communication. Above all else, a seeming lack of tact.
A developer standing alone can be evaluated by one set of metrics but when added to a group of other developers many of those metrics can be overridden by others and become meaningless. In simpler terms, teamwork.
I do not think developer grading is impossible, but there is so much more context involved. The "score" is dependent not just on the company, but the time and place in the developer's and the companies own life cycle. The perfect fit is always subjective -- these are organic life forms not rigid machines.
When you reduce a person down to a scalar, you're inevitably losing most of the signal in the different variables which go into that calculation. I am extremely skeptical that it's possible to come up with a model which makes that scalar useful to a hiring manager across a pool of candidates, even if you're some kind of data-science messiah. My .02 is that applicant scoring this way is inherently broken from a signal to noise perspective. (In fact, I bet if you just took GPA as the ranking metric, its performance would be superior as it's more competitive/harder to game, despite GPA being widely acknowledged as a subpar hiring metric - at least in my experience.)
I like that. An "in your own words" monolog can go a long way to help recruiters understand the type of person they will be dealing with.
That also means the recruiter(s) need to understand the questions they're asking. Technical merit is all well and good, but how well can a recruiter process the answers they're getting? This can't be a bullet point questionnaire with blind matching of answer "C" to question "1". Sometimes solutions aren't so black and white.