Yes, they are subjective because someone is looking at it and determining what they think based on eyeball test. That is in essence subjective. Objective would be whether a pass is completed or not. Subjective would be someone deciding if that pass was a good pass or not. I didn't say anything about whether or not someone understands player responsibilities.
Seems you are the one with a vendetta about this stat, not me. I don't have a vendetta because I couldn't care less if these stats exist or not. I couldn't care less if someone thinks the stats are dead on balls accurate or if they are garbage. In order to have a vendetta about the stat itself, I would have to care that it exists. I don't.
My comment was not about player grading and whether it was accurate or not. It was about what NFL teams pay for... and it isn't player grading.