Nobody has tried to systematically apply AI tutoring for adults. AI tutoring for children is easier because there are more people who understand the domains that need to be taught to children and can evaluate if the children have grasped the concepts appropriately.
It is clear that a personal human tutor can achieve incredible results, and almost everybody who has revolutionized any field you might think of is a product of such a system. Scaling that would be immensely valuable to society.
We should do it because of the huge benefits to society. The fact that it is easier than doing something with marginal benefit is why we should do it first.
The aforementioned people who revolutionized their fields are the demonstrated benefits. If we're going to stop a technology that could multiply that before it even gets to testing, it shouldn't be done on vibes.
And despite the hype, the jury is still out for how the results are for adults using AI