Anyone who's ever tried selling something knows that building something is not even half the battle. Putting engineering on a pedestal above all others serves no useful purpose (I say that as an engineer myself).
Engineering is solving a problem or need.
Product creation is trying to artificially create a need.
Marketing and sales get involved in the latter. Engineering is a byproduct of need and requires no marketing.
If I market a music band, I create no wealth, I facilitate the exchange of wealth. I am not saying that this is bad, but I am saying that the creator is the basis on which everyone else operates.
I agree value can technically be created at the base level by controlling production of crops and things. You are right, but still this is dependent on the producer.
@bwarp you are right, engineers usually have clients and contracts for which they build.
When you really dig into it, this idea of "creating value" is pretty damn complicated...