That second comment isn't making that statement though.
It's saying that: cost vs revenue is something we can see.
If I buy a plow for $2,500 and it enables growth of $5000, then arguing "the plow was expensive" is a moot point.
It doesn't make any argument about measured productivity, only investment vs return.
The difficulty in measuring productivity is the attribution. How do you know the new plow enabled growth?