I am someone who has changed development jobs quite a lot, far more than the average for my seniority.

Skill in software engineering can't just be measured by skill at writing the language, and this is trending forward faster and faster. The really accomplished engineer is one who has experienced many teams, many managers, many processes, and many deployments.

The accomplished engineer is opinionated about testing methods and about code readability, because he has suffered under many misconceptions about these things and taken the time to consider the alternatives.