I think the author you quote made a decent overall point.  His last sentence is wrong, in my opinion.  When China opened its doors to trade, for example, the result was reasonably predictable.  Jobs that didn't require a highly-skilled worker went to a country with a large pool of unskilled labor -- that large pool translating to lower costs.  Ricardo was simply taking Smith's division of labor a step forward to build a trade theory at a time when economists were at war against mercantilism.

Conservatives want live babies so they can raise them to be dead soldiers. - George Carlin

The point about "full employment of resources" is also key. In a world of global industrial overcapacity, industry location can have huge impacts on employment and wage structures, as people living in the US "rustbelt" well know.