Why is there actually the annonymous/Guest Review mode?

The guest/anonymous mode is there for those fanfiction.net users who only read stories and don't write their own. Most of them don't bother making their own profile, but might still want to respond to the stories they read. I was a guest reader and reviewer for years myself.

It's also useful for people who have accounts but cba to log in to review, or just have forgotten to review - something else I'm guilty of myself.

The majority of guest reviews I've seen have been pleasant, or at least constructive criticism. It's the minority which are flames.

If you do have problems though, I believe that it is possible to adjust your account settings so that anonymous comments can't be left on your stories.

That mode is designed for Net-surfers who don't have a Fanfiction account and don't post stories online on that site. The mode allows the readers to comment about stories they're leitura without actually having to go through the troubles of securing an account first.

I'm still an anonymous reviewer on Fanfiction, por the way. That mode is extremely useful for me, because I can easily send a few smileys or motivational comments or even help the author out in a pinch without signing up.

As for the flames- bullies just take advantage of the privacy that the anonymous mode offers. You can't really do anything about those people, unless you want to get things serious por addressing the police or something similar.

(PS: If my response resembles any other's, then I apologize, because I don't intend plagiarizing or lifting sentences from someone else's work!)