Earlier quoted context omitted.
Because I apparently need affirmative check-the-box consent before I can actually use those ad networks. I'm not doing anything shady: all the information I collect and why I collect it has always been in my privacy policy. But making people have to opt-in to see ads on the site is a big problem.
You can do non-targetted ads without explicit consent as far as I understand. You only need it for the extra personal information use. Sure it's a bit worse for the publishers. (But I'm happy with that)
Mom and pop publishers who don't have the resources or ability to staff their own ad sales team are going to be in trouble. The big players who can work around this obstacle are going to be fine. I'm not happy about this.