I completely disagree - do enough, or failing that, nothing. That is enough to solve the well-defined problems.
Giving extra to your employer for the same money is a recipe for exploitation. Additionally, “extra” tasks are less defined and therefore more likely to be wasted effort.
This comment does not make sense as a rebuttal to the article.
The author is arguing that you should use spare time you have after doing "enough" on things that enrich, educate, and grow yourself instead of simply doing more of your "normal" work. They state very clearly that they think you should not do additional work items that provide clear value to the business. They are saying you should give extra to yourself, not your employer.
Giving extra to your employer for the same money is a recipe for exploitation. Additionally, “extra” tasks are less defined and therefore more likely to be wasted effort.