I agree and I also disagree with this post. I agree, because as a writer it's not my job to kill the career of someone else with a cruel review. I have better things to do and reviews are used to work vica-versa. People may get what they give.
But I disagree with a part in your post Regan... this one.
Boy am I glad I took down my negative reviews! Shortly after signing with NCLit, I got an insider’s view of what bad reviewing can do to you:
You won’t get signed.
Before I went on sub, my agents warned me to stay professional, keep my online presence calm and clean, and avoid negative reviews, comments — anything.
First of all, whoever won't sign you because you ever had or have an opinion about something, that's highly unprofessional. It's like: "Be a robot, you can't have an opinion, otherwise you won't get signed.". Now, if an agent can't handle a client and it's communication, i.e. a single bad book review prior of publication, or because of a personal, honest, but modest, normal opinion, that agent is absolutely useless.
Just like “talking bad” about a book can keep you from getting an agent, it will also keep you from getting a book deal.
If this is keeping someone to get an agent, back to the previous paragraph. Also who is going to determine what is "talking bad"? Them? What is the standard? Can we get a guideline for this at all? Is there a guideline at all? Of course not. So, actually this sounds as a poor excuse for something what some agents are unable to handle. What they forget, writers are usually good with words, better then the average reviewers.
And TRUST ME: editors may love your book, but hate your online presence — and that means you won’t get published.
First of all, they must sell THE novel in the first place, not our image. Of course a proper image is good for everyone, but this "hate your online presense" is also highly unprofessional, because who is going to decide what is good and what is bad? Them? Is it bad if you have a modest opinion? Is it bad if you're writing an opinion if someone is asking you about a subject? Of course it's not bad.
Trust me: agents google you.
We're also watching and googling them. So, what's the point? Agents are making black list about writers, but writers are also making black list about agents too. The problem is; writers are creating the sellable materials, the worlds, the novels, not the agents or the editors. That's what few used to forget sometimes. If a writer is on an agent's blacklist, that writer still has his / her novel to sell. If an agent is on a blacklist, that agent can say goodbye to his / her career.
The essence is: it's not an agent or an editor's job to moderate you in your private life and it never will be. You must act as a professional, that's true (See my first paragraph.). But whoever is trying to tell you how to live your private life, especially prior the first contact, otherwise you won't get a job, that one is living in a great illusion (And this is also a direct invasion of privacy and against freedom of speech.).