Output

In the built environment, a good engineer or technical expert will produce a document, or they will at least produce something tangible (this might not directly apply in the IT/Tech environment). 

Good engineers demonstrate competence through their pictures and words. There’s no way around it: for a technical role, the output is tangible and “written” – whether a drawing or report or a calculation or a plan. 

A manager or leader can do an excellent job of managing or leading, without necessarily producing a document.  No competent engineer can do that:  an excellent engineering job is defined by producing something tangible.   If there’s nothing tangible, what was engineered.