The other solution, in addition to adding authors, for lazy bloggers is using blockquotes. You read something in the media or on another blog, copy it with Control-C and then come to your own site and paste it with Control-V. Add a quick sentence like, "So-and-so said such-and-such," and you have instantly and almost effortlessly created a post.
I used to read Andrew Sullivan at The Atlantic because he provided reasonably intelligent thinking from a conservative viewpoint, even if he did go a bit overboard with pet issues from time to time. But he devolved to one of those bloggers who merely adds brief comments to lengthy blockquotes, and I gave up on him.
The blog Balloon Juice has long been one of my favorites, but I've lost count of the number of authors John Cole has added, most of whom are about as interesting as watching paint dry. The comment threads tend to be highly entertaining, but Cole's posts, and increasingly all posts, are more and more consisting of brief comments tacked on to lengthy blockquotes.
Fortunately, as my favorites get tired and resort to cliche methods, new bloggers crop up. The Internet is a vast place. Maybe I'll get tired of doing this at some point too, but I hope I'll just quit writing when that happens, rather than resorting to hackery.