How do you plan to distinguish between anonymous postings, and postings from throw away accounts? I mean, it's trivial to set up a new account, and while anonymous postings don't really excite me, they aren't worse than postings with throw away accounts.
Besides, if postings should be judged by its content, it doesn't matter who posts them, does it? Who posts something only matters if we would have individual filters, so I could ignore certain people - or make certain posters more prominent. And then when you have individual filters, everyone could decide whether or not (s)he wants to see postings from anonymous monks.