That's a pretty big assumption that offering this service would not result in these users also spending more time on other, non-education related content on YouTube that is monetized. There are also other ways to monetize the product.
I think that two things can both be true: creators should be paid for their work, commensurate with the value they provide, and learning should be free (or of negligible cost) to the person doing the learning. There are exceptions to the latter when there isn't a platform involved, like personalized tutoring or coaching, but in general.
YouTube can achieve both of those goals, and advertising is not the only solution. What bothers me most about this announcement is that they aren't doing anything _new_. This is basically a carbon copy of Udemy's value prop, leveraged by YT's existing massive scale. Other than the videos being hosted on YouTube, it doesn't do anything that other platforms haven't already been doing for years.