Pyan and OR have the right of it. Editors tend not to make decisions about which books to publish. Marketing makes these decisions ... The publisher responded to public demand created by places like the Chrons, as opposed to a good editor saying "this is a really talented author, we should market this book like crazy".
Not quite true. The marketing department doesn't even get to look at a book unless an editor decides to pitch it to them. Marketing has a veto, but books are still chosen by editors. (Who, admittedly, have a pretty good idea of what marketing will like.)
And the demand created by online forums is miniscule compared to the numbers a book is expected to put up these days.
I think that reader enthusiasm for certain authors does more to fuel online forums than vice versa. Word of mouth is powerful, but the majority of it doesn't happen online.
As far as publishing houses, I think the big difference these days is that none of the big ones are family businesses run by people who genuinely love books. The days when a Raynor Unwin could tell his father that he thought a book would lose them money, nevertheless he believed the book deserved to be published -- those days are long past.