It's good to know the system I'm talking about is mostly dead; the committee of unknown engineers always felt bonkers to me. That being said, a ratio of 1:5 or 1:6 of bad incentives at promo committees still sounds pretty suboptimal to me — when I was on calibration committees at FB, it was super rare for me to come away with the feeling that the wrong thing was being incentivized or rewarded at an engineering level (oh boy was product management a different story, but that's a different post). There were a couple times where I disagreed with an outcome, but that was like 1:150 or better.