That explanation was not written by Gowers at all (his name appears on it now that the answer was marked community wiki, becuase he is the most recent person to edit it, to fix a typo), and indeed although Gowers is certainly brilliant, this is far from his domain of expertise. That answer was written by Martin Weissman (username: Marty), the author information is at the bottom right corner of any answer and here says "Marty 98%".

Also, take a look at Minhyong Kim's answer.