I'm not quite sure where you're getting "performance = maximizing units of output" from my post, as the whole point was the difference between squeezing out a little more code vs. keeping the team on track doing actually valuable stuff. Either way, I think we mostly agree here: the EM is the face of the team who makes sure the team, as a unit, is doing valuable work as a sustainable pace that's understood as such internally.
However, to be clear, software teams, engineers, and engineering managers are absolutely evaluated on their performance, which is a complex and subjective metric, and the manager is generally the one held responsible for it at the team level.
