This is a bit of a strawman. The fact is that the people (on the assembly line) following instructions are less valuable (and thus will get paid less) to a firm

This is a bit of a strawman. The fact is that the people (on the assembly line) following instructions are less valuable (and thus will get paid less) to a firm than the people "at the top of the money funnel" who are the decision makers. Whether or not advertising has intrinsic value doesn't affect this.