Poul Anderson's
The Man Who Counts spells out its message right at the end. The Man Who Counts is not the engineer but the man who motivates the engineer and everyone else involved by doing whatever is necessary to ensure that the job gets done: paying salaries; chivvying; coordinating; organizing; negotiating, bribing, even cheating at dice to gain money to bribe with, etc. Van Rijn even manipulates his opponents into doing what he wants them to do.
Sandra Tamarin explains most of this to Eric Wace, then, when Wace begins to reply:
"'...we played our parts too...Without us, he...,'"
she interrupts:
"'I think, without us, he would have found some other way to come home...But we without him, no.'"
-Poul Anderson,
The Van Rijn Method (New York, 2009), p. 511.
Here, I think that she goes too far towards almost deifying van Rijn. I grant that Sandra and Wace would not have gone home without van Rijn whereas he, even if stranded alone without any human companions, would have done his damnedest to reorganize Diomedean society for his own ends. We see him doing this. But success is never guaranteed and would have been even harder without Wace's engineering skills. In that sense, everyone counts. Human labor is effective because it is collective.
Van Rijn succeeds where many would have failed. By sheer luck, he was not one of those who died when his skycruiser was sabotaged. He could have been knifed in one of the fights. Here is an idea for an sf/detective story: van Rijn, stranded on another barely habitable planet where a fellow Master Merchant has made many right moves but has finally succumbed to hostile conditions and adverse circumstances, must reconstruct his dead colleague's actions in order to determine what went wrong and to find out how it might be possible for a second group led by van Rijn to survive.
The point about not doing everything yourself but motivating those who can perform particular tasks to do them is amply illustrated in Anderson's
Tau Zero. The crew of the Bussard ramjet hurtling at near light speed between galaxies needs to gather astronomical data from the relativistically distorted galaxies. One man on board has the knowledge and skills for this task but is completely demoralized so the practical problem becomes not how to observe the galaxies but how to re-motivate the man who can.