People are funny about parenting books. Even among people I'd generally consider fairly book-friendly if not book-obsessed, there's often an attitude of disdain and dismissiveness about taking parenting advice from a book. Of course, the disdain appears most prominently when the book advice disagrees with the disdainer's. But even when it's not a case of competing expertise, there's a common sense that parenting is just isn't the sort of thing that experts can help with.
And I understand and even to some extent even agree. Parenting books can only talk in generalizations and averages, and when your child lies outside the catchment of the generalization, the advice isn't much use, and can be demoralizing. I remember reading (it was Ferber or Weissbluth, I can't remember which) that there's no such thing as a kid who's just naturally a bad sleeper -- there are only kids who haven't been shown how to sleep well. Which I read, not surprisingly, as a blistering indictment of my parenting. Not helpful. And now that I have more confidence as a parent, I can say with assurance that that's nonsense, that while I'm sure any baby's sleep can be improved in various ways, there absolutely are sleep-resistant kids, and mine is absolutely one of them. So I support taking expert advice with a grain of salt, and I certainly support skepticism of any advice that undermines you or seems not to jibe at all with your own observation.
What I don't understand and can't support is not reading the books at all. I can't count the number of times a parenting book introduced me to a concept that had never crossed my mind, or offered a tactic or solution or small but crucial course correction that I found helpful. Even just reinforced something I'd done at first instinctively, or backed up a decision I made thoughtfully but absent expertise.
I think we sometimes have this notion that parenting ought to come naturally. And to some extent, it does. I'm pleasantly surprised by the number of times I've done something without thinking it through, without making a conscious decision about it, and had it turn out very well, turn out in some cases to be exactly the thing the experts say you should do. But just because it's possible, even common, to stumble blindly into doing the right thing doesn't mean we shouldn't be aiming for conscious and conscientious parenting. I've observed too many parents whose instincts are flat-out crappy to have any real faith in instinct. And though I often get great advice and the benefit of other people's experience by talking to friends, there's no way for casual conversation to cover parenting topics as broadly or thoroughly as a book can.
Or, more accurately, as a whole bookshelf can. Because you can't just read one book, or a few books. Because the experts disagree, and you may disagree with the experts. If you only read Dr. Sears because you're all about AP, there's a lot of helpful information you'll never get, a lot of dissenting opinions that may suprise you by ringing true. Sometimes the books that challenge your cherished notions of parenting are the most helpful because they're the ones that make you think hardest about why you make the decisions you do.