That article makes it seem not so bad in the opening paragraph when it talks about it being an exploit for an outdated version of WordPress. Then it says the exploit was fixed only about 2.5 weeks ago.
I do manually check my WordPress sites every so often to make sure they are updated, but that is probably on average about once per month. So yeah, thank goodness for WordPress auto-updates, because if not for that, my sites would probably be vulnerable as well.