In order for someone to feel effective at a task they must have been able to measure their progress throughout the duration of the task.
Imagine if you were working as a steel bender and all you did was just put sheet metal into a machine, press a button and then take the bend piece out when the machine was done operating.
It's mind numbing, tedious and disheartening work... But you can measure your progress, if you can see the stack of sheet metal disappear and the pile of bent metal form beside you.
If you removed one or the other as a means of progress, the other would still remain "I did two stacks of sheet metal today" or "The product reached the height of my head"
Now imagine you could never see the sheet metal disappear or the product be stockpiled.
You would never have any sense of progress and thus no means of measuring success or competence, at the end of the day.> Why are arists always so crazy?
"Art is subjective."