Why give away for free what you are trying to sell in your books? That makes no economic sence.
I have bought books for the information contained, or a reference made, in one paragraph, that was reliment to the study I was interested in at the time. If I could get that information for free, I wouldn't have bought the book. Thanks David Upton for your post. You have saved me a lot of money by posting your "quotes" with references.
From what I have observed, most of the people that have posted on these sites are peoples who seem to research for personal reasons, or have a personal axe to grind, and usually have no primary commercial interests.
To be honest I have found more "nuggets" of informational "Gold" on sites like this than I have in most of the books that I have bought. So I can understand why authors do not wish to share their research so freely if it would impact the sell of their books.