An excellent question. It looked strangely familiar to me, which is why I initiated a Google search which led to the discovery of the referenced URL.
As far as having been used on FR before, I can't be sure; if it had, it should show up in a google search. It didn't on the phrase that I searched last night, but it might on others.
Maybe the post is not identical to one used before, but the technique is identical. Take half a dozen paragraphs from an outside source, toss in a few phrases of expansion and comentary, and suddenly it's yours. I wonder if this works on college essays when they are checked by internet robots.