I like how they promote engineers based on "mastery". This is very different from Google, who treats promotion as a tool. That is, mastery often is not the only consideration. Sometimes it is not even a consideration. Of course, no one would say so officially, but more than one VP and director expressed this principle in different ways. And we can see the results: the promoted can be most important, most influential, most needed, or most trusted. Mastery of engineering is not necessarily in the equation.