I'd just like to point out that "anonymous" is a pre-existing term for all people who choose not to identify themselves, so any time a journalist says "anonymous" did something they are merely professing their own ignorance, regardless of whether the A is capitalized or not. That said, the term seems to have become popular among a particularly low-status sort of person, so I advise everyone to use pen names and explain their unidentifiability in complete sentences.