I blame Frank Miller.

Back in the days B.F. (Before Frank) the comic book Editor Gods had decided that the job of making a comic book should be broken down so that hordes of different people worked to create it together. This way the people who were best at these specific tasks could put out more work. After a while it got out of hand, with jobs like Plotter, Scripter, Penciller, Inker, Colorist and Letterer (eventually they would have broken this job down even further: "Ted, you letter the consonants. Bill, you’re on vowels, and sometimes 'Y'").

Then along came Frank, who blew the doors off, and suddenly every artist thought they could write.