Fantasy TOP - land of best fantasies

I ran across this post from a Literary Agent today, and it raised a question I have wondered about for some time. First, the relevant excerpt:

Of course, there will be exceptions, but overall, I think you should "just say no" to reviewing books you don't like. There's no sense throwing a fellow author under the bus just to be different or to have the freedom to express yourself. Your review is a valuable promotional hit for the author of any book you feature; why not reserve this gift for the authors you appreciate?

Please note: I'm NOT saying you should only say good things about the books you review. I'm saying: only review the books you can honestly say some good things about.

First, remember this post is from a literary agent. With that said, it sounds to me like she is suggesting that reviews are written for the benefit of the author, not of potential readers. Which leads me to my question:

Should reviews be written for the benefit of the author, or the potential readers?

My Answer:
I write my reviews for potential readers only. Sure, I like the fact that if I like (or love) a book, my review could benefit the author. And there are a LOT of authors out there I really like. By nature, I am also a people pleaser..meaning I don't like to be negative. However, I feel like my reviews are a service to potential readers. I try to explain whether I liked the book and would recommend it. I also try to detail what I liked and what I didn't. All of these thought processes are geared toward trying to help other readers determine if they might like the book. Even if I didn't like it, I try to find ways to discuss what type of reader might enjoy the book.

I will say that I think reviewers should remember authors are real people, and have feelings just like the rest of us. This means we should be respectful towards the author..no name calling, insulting, or stuff like that. But if I thought a book was bad, I feel I owe it to those who read my blog to say I thought it was bad (with an explanation why, and without making a personal attack on the author).

Additionally..who wants to read a blog that posts only positive reviews? I think readers will accuse that blog of being a sellout or tool of the publisher, making that blog's reviews useless. So just as a matter of course, I think I have to discuss the books I didn't like. Sometimes I even write a post to say I just couldn't finish a book, though I won't label that post as a review. Even though I consider myself a nice guy, I don't feel the "if you don't have anything nice to say, don't say anything at all" idea applies to reviews.

So..what do you think? Do you agree with the literary agent's post, who seems to imply that reviews should benefit the author, or only positive reviews should be posted? Or do you think reviewers (like me) should be writing to help potential readers, posting both positive and negative reviews?

To reiterate: I think reviews are for potential readers, not authors. If I want to "help" an author, I will host an interview or run a giveaway. I think those are the best ways to directly help an author, leaving the reviews to help the readers.