Although he's right that people are tired of readding friends on each network, one flaw is that "friend" has different meanings. On some, it's simply "This person is my friend". On some like Facebook, it also means they can see information about you that others might not. On LiveJournal however (which was created by the author of this article), it goes far beyond simply "friend"; it indicates which journals you want to read, and who can see your "friends only" entries. So conceivably, who I want as a friend on Facebook isn't necessarily the same as who I want as a "friend" on LJ.

Now theoretically this can be handled in that "people whose journals I want to read" could be a subset of anyone I list as my friend (i.e., you have an option for each friend whether you read their entries, whether they can read yours, or whatever is specific for that site). But that's more hassle for individual users.

It's recognized that users don't always want to auto-sync their social networks. People use different sites in different ways, and a "friend" on one site has a very different meaning of a "friend" on another. The goal is to just provide sites and users the raw data, and they can use it to implement whatever policies they want.