So your argument is the draft year cut off sets a point of reference to track prospects thereafter- as to why it's superior. My point is this is a fictional arbitrary cut-off anyways. Why make the frame of reference at that point? You used some physical maturity argument earlier but no one's to say, as a generality, any prospect's physical maturity peaks, bottoms out, or plateaus at ~18 years of age, on any calendar date within the year. Sure, they can be 364 days apart by some extreme reference point using age, but it's not inherently different than by some extreme draft year analogy (in the opposite direction) is all I'm saying. I'm not exactly vouching for either- I do lean towards age but not enough to ignore all context.
I think ultimately, you should use both draft and age year with context to judge a prospect. Or else you paint clouded narratives either way, using the extremes of both.
I don't have a side in this argument and I'm not faulting your argument in the other direction (for what you claim is a flawed argument). I think your shooting one extreme and perhaps, the other poster is shooting the other- when it should really be closer to the middle.