But if Youtube didn't monetize, presumably with the rise of the Youtube star, content creators wouldn't make enough money and would not publish there. So if you think of it from this angle, Youtube needs to go to war with ad blockers simply because their content creator, the users adding value, require them to do so.
I also wonder if the rise of the "this video is sponsored by xyz" segments in people's videos have cause more harm. That ad money that is circumventing Youtube entirely, paid directly to the content producer. So Youtube might be "jealous" of this revenue and wants to encourage its content producers to let them run ads only? because it's easier that way?