If you are correctly following an Agile process such as Scrum, the productivity of each team member can indeed be quantified. You may think it's pure bullshit numbers, but the ratio of story points to hours worked tends to stabilize over time and give management an idea of how productive you really are.
>If you are correctly following an Agile process such as Scrum, the productivity of each team member can indeed be quantified.
No, no, no, a thousand times no. Tracking story points by developer is the diametric opposite of "correctly following an Agile process". It gives team members, individually and collectively, an incentive to game the system, thereby corrupting your metrics and estimates. You are literally begging your team members to lie to you.
Any competent lead should be able to identify who is more and less productive without using what is essentially micromanagement by story point. Story points should only ever be tracked by team for overall velocity measurements.