When you respond to a sentence using the words "generally", "tend to", or "usually" with one using the words "not all" or relatives, you are effectively conceding the point. Correlation cannot be denied with a mere counterexample.
"Not all engineers are [figurative] robots" is certainly a fact and was meant as an upper bound on the number of engineers who believe that photography is merely technical in nature. I'm questioning whether the lower bound is statable as "generally engineers believe this", and claiming that I don't believe it is.
To further clarify my opinion: the line drawn by the author is too black and white. Its inhuman and unemotional itself to assume that another large group of humans can't see the emotional and human side of art.