Actually yes, it does affect authors and publishers. I know as an author and newly started publisher that people actually not starting some series because they wait till all the books are finished to buy results in several new trends:

1. not publishing new and unfinished series

2. Not buying translation rights because some big publishers pull series after sales if the second edition are much lower than the first, even if it is because the "I will buy the rest when the all come out" effect, actually fueling more people to not buy series

3. Rapid publishing, putting out a new book of a series every couple of months, because they have bought the finished series. Creating unrealistic expectations with readers who then wonder why their "author" has not published something for "so long" because other work only gets picked up after the whole lot is written, which can take years, by whitch point the author is manly forgotten and might not get picked up again. Unless offcoarse it was an extreme succes.

But yes, it has changed a lot.