The wrong is an obnoxious manner of redefining communication protocols (in this case, language) in order to support the premise that the author is always right. In this example, the premise is that Facebook users (standard and accepted term) do not derive any benefit from Facebook but are only exploited by it. This is obviously false, since if people did not derive any benefit from it, they would not voluntarily flock to it in millions. But by refusing to even admit this possibility and constantly hammering this mistake into the reader, Stallman tries to reinforce his (weak) point by repetition, not relying on cognitive facilities of the reader being enough to get this point without it being repeated 60 times. I don't know about you, but for me it's annoying and obnoxious when even true point is repeated to me 60 times through a short text. Even more annoying if the point itself is so trivially weak.