As one commenter on the article notes, there are a lot of idosyncracies in the mainstream publishing biz that decide who gets published the old-fashioned way and who does it on their own. It has always been assumed that mainstream publishing represents a filter for quality. Most book review sites with any readership use the mainstream publishing process as one of their filters - hard to blame them, when the alternative is trying to sort through a huge mass of additional material.Quality is clearly sometimes a factor in publishing - on average I'd bet mainstream books are "better" than self-published. But I'd also guess there are some works of value out there that got ignored for some other idosyncratic reason. If someone is delving deep into a subject and is partial to books, sticking with the mainstream means putting your faith in a relatively small group of people to decide what is worthy of your attention.