You need to reread the article. The word free is not there.
I took a liberty in expanding the argument. In the end, Williams is writing something, if taken to it's logical conclusion, that would state that self-sufficiency is something to be avoided if the pain in reaching that goal is too great.
The examples of coffee, cocoa and spices, in this regard, is a very bad one. People could live reasonably well without any of them. Try living without steel, electronics, concrete, plastics and a host of products produced through heavy industry, which is increasingly disappearing in this country. The industrial base that produces many of the products we depend upon, but never think about, is leaving these shores, never to return. In the event that our trading partners (in some cases, potential enemies) deign it necessary to trade with us, they will.
When it no longer suits their purposes to do so, they will cut off the flow, and we'll all be up the creek.