The example given is fridge cleaning, but tasks outside your narrow job spec can be very useful. For instance, if you are hired as a software tester, and snag

The example given is fridge cleaning, but tasks outside your narrow job spec can be very useful. For instance, if you are hired as a software tester, and snag a task setting up the automated build system, you can turn that into a higher paid dev ops careeer. Some people thrive in highly structured environments where they can optimize for metrics and get promotions - they do well in big companies. Others collect skills and achievements and use those to push their career forward - they do well in small companies and consulting. The world needs both. With that said, knowing when to say no is very important as you say.