Why do many historians regard the printing press as the most important invention of the past millennium?

The alternative would be a scribe or passel of scribes to publish your written words. Let us say you were a scientist, poet or Mozart. With the press came wider audiences but more importantly ... money. You could print 1000 copies and make a few bucks. Most important was that it made possible the invention of newspapers via penny galley sheets. The Renaissance was all about lifting the fog of the middle ages, and selling a lot of bibles. The other thing ... it made possible a dictionary of the language. Since most folk could not read, it invented the effort push to universal literacy. As usual, it benefited the rich first.