Exactly. But since it seems pretty much impossible to retain impermanence in the digital sphere (real-life impermanence relying, of course, on the fact that the information is never recorded to a reliable medium) anonymity is a necessary crutch.
The author's real point is that argument made by google and facebook ("there's nothing wrong with more-or-less eliminating anonymity online for the same reasons that we do just fine in meatspace without much anonymity") doesn't go through, because of the differing levels of permanence between digital and real-life interactions. Therefore, if you want to argue one side or the other, you have to do it with those differences in mind.
The author's real point is that argument made by google and facebook ("there's nothing wrong with more-or-less eliminating anonymity online for the same reasons that we do just fine in meatspace without much anonymity") doesn't go through, because of the differing levels of permanence between digital and real-life interactions. Therefore, if you want to argue one side or the other, you have to do it with those differences in mind.