What incentive does a blog author have to produce excellent work? Ego, satisfaction, reputation, altruism ... Many others, and we have an incredibly diverse, informative and entertaining collection of work today, much of it distributed for free. The authors get whatever the authors get.
I think the web is evidence that copyright monopoly is no longer necessary to promote publication. People figure out how to get paid in some way, or they get some other benefit.
I've learned at least as much reading blog posts and other web content as I have from my college texts.
Copyright is not the only way, and I don't think it's even necessary anymore. People write and converse because they want to write and converse. Some of those want to make money from it, and they'll figure out a way, either by selling their work directly or by using their work for reputation to gain entry to employment and other activity.
I don't think the founders sat around thinking up ways for people to be paid. The money earned by copyright wasn't the point, that was just the necessary incentive at that time to achieve the goal: that people wrote for publication, so that people could read.
Without copyrights, what incentive does an author have to produce new work? Someone will take it and redistribute it, take credit for it, or otherwise profit from it.