I agree with that. Engineering managers are ex-engineers after all so the ratio 10/90 applies at any level. What if you promote a "bad" engineer? She/he would

I agree with that. Engineering managers are ex-engineers after all so the ratio 10/90 applies at any level. What if you promote a "bad" engineer? She/he would have a much bigger impact on people = more impact on the company. The problem is not about engineers vs managers. The problem is about micro bubbles within a company which create micro cultures that are often driven by these (micro) managers. A solution would be to put everyone at the same level. That sounds very naive and provocative... but after all, there hasn't been much innovation in that space within the last 20-30 years. We manage engineers like we used to manage workers in a factory. I think the model does not apply anymore. That's just my naive/ideal world opinion...