Do authors need editors?

My last blog post was picked up by The Passive Voice, and has so far garnered 285 comments. There's a lot of interesting stuff there, if you have an hour or two to read it. My eye was caught by a comment from author Kathlena Contreras:

My experience with people acting as "editors" is that they've tried to change how I tell my story. And ruined it in the process. My point is that we, as artists of the written word, should stop asking authority figures to validate our work and have some faith in the vision we're trying to communicate.

It's often stated on indie forums that no book will be the best it can be without the help of a professional editor. I think this is nonsense. While I'm sure a good editor can contribute to a book, a bad one can ruin it. I've never blogged about the critique that Remix won on Authonomy from an anonymous Harper Collins editor back in 2010. Not sure why - maybe I didn't want to appear unprofessional. This is part of it:

Here’s how you might take your story into the real world. In this darker alternative, instead of dossing down on the roof terrace of a penthouse flat [sic] in London, for example, Ric would be living in a ramshackle shed at the edge of some property in France possibly inherited recently from the protagonist’s mother/aunt etc. She could come to stay for a few weeks, figure out what she’s going to do. 

He was telling me to change the setting from London, which I know, to France, which I don't. Yup, that makes sense.

But she hears noises, she’s disturbed, thinks there’s someone threatening in the night… doesn’t know what to do… tension builds… next day, she has a poke around, finds evidence of someone living rough, at first she thinks he’s dangerous but then they meet (right there, we’ve gone from a few pages to several chapters with new beginnings, red herrings, tension, uncertainty, plot twists). 

Several chapters where all that happens is a timid woman meets her neighbour. Great.

I think its [sic] unwise to cast a world-famous, very handsome rocker who’s only recently disappeared [in fact three years before] but hasn’t disguised himself at all and has just climbed some tall building [actually three storeys] in Hoxton as a ‘mystery stranger’. Better for him to be more like a cult figure who hasn’t been seen for years – bearded, a bit bedraggled perhaps… but suspiciously well-kempt as if he has money. Then let the relationship build up for a while before the revelations. 

Revelations of what, exactly? If Ric's living openly he can't be a murder suspect, so there is no plot.

I remember having to read this critique two or three times before I believed it. I wasn't foolish enough to take any of its advice. But I pity the poor authors that particular HC editor works with.