Book Platform Isn't Expertise
One of the reactions many writers had was that it seemed unfair that the commedian's wife should get a book deal because she wasn't a nutrition or food expert. She had no platform in the topic. She was just married to someone famous. I'd like to take a moment and disabuse many of an erroneous concept. Platform has everything to do with the writer generating sales by the mere connection to a book and nothing to do with expertise, except as that expertise feeds into the sales. I repeat - platform is all about the sales. That's all the publishers care about. I think it's an ultimately short-sighted view of their businesses, as if what the customers wanted didn't matter. But if you're going to deal with the commercial publishing world, you have to understand this.
I see many writers starting blogs, trying to get specialized certifications of knowledge, write articles on a topic, and generally show that they know about a subject. But few actually get somewhere. The publishers don't care if you have a blog or web site, unless it has lots of readers. They don't care if you have Ivy League degrees up and down your arm unless you put yourself into positions where you can promote your book. By the way, part of this can be nothing more than perception of the publishers; they think you're doing things that indicate an audience, and so assume you have one.
Until writers begin to understand this dynamic, they won't build an audience, won't have a platform, and won't get meaningful book deals.