What I think the big hurdle with the internet is is how conscious it makes people of every other writer. There's no room to breathe and naturally develop something. There's such a weight of easily accessible information and it can be accessed at such a rate that anything you do is unavoidably refracted through this vast web of poses, references and second opinions.
That's obviously true for someone writing pre-internet too, but the intensity of it is new and what I think the problem is. I suspect that if you locked someone in a room with loads of books, even if you forced them to read them all in bits and simultaneously, they would still fare better than your average internet user.