You may have high performers (and low performers), including people that perform very well in a particular context or even help the whole team performing better. There is no question on this.

Putting an actual individual factor on it and especially on engineer productivity, like we were at a line factory producing everything in a repeatable and measurable way is more questionable. 1x, 10x, 1000x? People here are discussing 10x becoming 2x, it sounds very mathematical. Now if there is an actual scale with an industry baseline and an individual measurement, I'm more than interested to learn about it and I think employers should fairly compensate engineer based on the scale factor you would put on your CV.