Good article. Like the author and others, I have often compared watermarking with locking your doors, too. We don’t leave our doors unlocked because it doesn’t prevent ALL burglars.
I would also add that where he talks about reporting infringers, you can easily send DMCA takedowns to an infringer’s site yourself. Many sites have a copyright infringement reporting form or email. Below is my go-to info for all the links and tips I have collected on this topic and would never remember anymore without them being in a document: http://www.redbubble.com/people/cschnack/journal/7750976-art-theft-copyright-infringement-find-it-act-on-it
Enjoy the reading! 🙂