The publishing process is traumatic for many writers. The writing - the hunt for an agent - the fairly small number of editors who'd possibly be interested. This is not a business for the squeamish or the easily hurt.
I realize that I am part of this traumatizing process. The trauma I inflict on writers hits its peak when they get my first red-penciled edit of their manuscript. Pages upon pages are scratched out. Whole sentences are deleted. Characters are removed. Dialogue is vastly pruned. And those marginal queries where I point out things that need to be fixed...! Let's not even talk about those.
I have been thinking about this because I am on a roll. The last five books I've edited have all received at least one starred review, and often more, in the key review journals. I take this as a reminder that I not only know how to spot talent but also know how to edit a manuscript to bring out its best.
But I can't deny that all of this does come at a cost to writers. A common feeling -- and one that I've heard put into words a few times when a writer receives my editing and begins implementing the requested changes -- is: "I feel like it's not my book anymore." I can point to at least a few occasions where writers have told me, long after the fact, that when they sent their final draft to me, they didn't care about it any longer. They felt that I'd pushed them too hard, forced them to make choices they were uncomfortable with, and felt somehow alienated from their own manuscripts. (Fortunately, the love came back when the books got those starred reviews and sold decently or well. There's an exception; one time a writer told me point-blank that my editing hadn't done anything to help or make the book successful, but let's not talk about that.)
I think the truth is this: Once you sign that contract, the manuscript is no longer yours. It becomes the basis for a commercial product into which many people (many competent, some highly misguided) have input. Everybody at the publishing house has a stake in making your book successful; and none more so than your editor. I've never - and I do mean not once over the course of decades - read a manuscript without editing it in my head as I went along. Probably the best one was only about 75% of where it needed to be; the worst was about 40% but the story wouldn't let me go and I liked the author's attitude.
I also believe there's a sort of illusion (among the unpublished) that writers and their agents and/or publishers always engage in love affairs of mutual adoration. That might happen in some cases, but I don't believe that I need to be my authors' best friend. Of course I have to be their biggest advocate; but I'm also their biggest critic. I hold them to high standards, which they simultaneously appreciate and detest. I'm in the middle of a battle now with an author who submitted the next book in a series - and it's just terrible. You can imagine how these conversations are going, or not going. But that's the business.
So, back to your manuscript no longer being yours. A manuscript is like a child - You have to groom it to take care of itself in the world, because once it's out there, you're not there to protect it. You have to steel it against the likely criticisms, the jabs, the negative reviews by eliminating the weaknesses and giving up elements that meant a lot to you but, sadly, don't fit with genre or readers' expectations. Once it's out there, it's no longer yours; but, if we've done our jobs right, it's grown into something that has a much greater chance of commercial success.
There is a bright side to all of this: No matter how much mystery writers feel tortured by the process, it's NOTHING compared to what screen writers go through as they attempt to get movies produced.