Do writers literally have sex with their characters?
If they can't then they don't, If they can, then we don't know what goes on behind closed doors. The question is can they to begin with.
The sex robot/doll is (advanced) masturbation with an object. But a writer can masturbate to their character through creation of sex scenes/sexual imagery. Both are objects that carry female personae imagined by the male and completely controlled by the male. Both can be made to do degrading things. One in a 2 dimensional the other 3 dimensional medium. I don't see why the difference in medium is what makes the difference, as isn't this a mental phenomena we're talking about? Dehumanization through complete male control of a representation of a woman?
Do they use their characters as simulacra which directly substitute for a flesh-and-blood relationship?
On some levels yes. There are articles on Forbes about it.
https://www.forbes.com/sites/booked/201 ... 5d3e2c7f4f
That’s why authors enter into an intimate relationship, a kind of lopsided romance with their characters, no matter how virtuous or flawed those characters may turn out to be. No part of writing a novel is more important than this visceral, under-the-skin, psychological connection.
From there it's just short move to say you're too busy for a real relationship, you have to stay in and write, which I know I've said, and you're there.
Is there a preference for such substitution over real relationships because of the degree of control it offers?
We can't go into people's heads and know what they really think, but can there be? Absolutely. All we're talking about is a writer who would rather stay in and have adventures with their female character through creativity over going out into the world and seeking a real relationship. Why do many single men control sexualized female characters in video games? Surely about control and risk free interaction.
You can probably find exceptions in some fanfiction or wish-fulfillment writing.
You could probably find many exceptions if you raided the computers of writers and the scrapbooks of artists.
Writers can make misogynistic porn of their characters which no one else sees. Same as we aren't seeing what people can do with sex dolls/robots behind closed doors.