Well, of course, you can have it both ways. Some forums allow you to “post anonymously.” That is to say, you are still required to log-in, but you do not have to reveal your identity in a particular post.
A big concern for me would simply be ... spam!
Perhaps we folks on “the west of The Pond” have it luckier than our compadres in England, because I do recall BrowserUK in particular saying that many hours are spent each day eliminating the pure-junk robo postings. That’s a waste of time for everyone. (But we hugely appreciate your ongoing efforts!) Requiring an actual identifiable login ... identifiable, at least, to the gods ... would perhaps help to reduce that problem. Now, you can have the “anonymity” that you perhaps crave, but you are still accountable ... and you retain the ability to edit your posts, which right now can be lost purely by accident if the session-system takes a powder.
“Post Anonymously” would simply become an attribute of the message. If it is checkmarked, the posting appears to come from Anonymous Monk, and maybe it doesn’t count for or against your XP. (Sure, people who care about XP will play with that feature to their own score-advantage, but ... (shrug) ... who cares, really.) Whether or not it gets counted against the phantom AM user is also who-cares. I am more interested in not “losing” control of postings due to a pure-technical glitch, and in reducing the opportunities for spam-bots however slightly.