Having an actual human who is a "brilliant private tutor" is an enormous privilege. A chatbot is not a brilliant private tutor. It is a private tutor, yes, but if it were human it would be guilty of malpractice. It hands out answers but not questions. A tutor's job is to cause the child to learn, to be able to answer similar questions. A standard chatbot's job is to give the child the answer, thus removing the need to learn. Learning can still happen, but only if the child forces it themselves.

That's not to say that a chatbot couldn't emulate a tutor. I don't know how successful it would be, but it seems like a promising idea. In actual practice, that is not how students are using them today. (And I'd bet that if you did have a tutor chatbot, that most students would learn much more about jailbreaking them to divulge answers than they would about the subject matter.)

As for this idea that replacing effort not being a problem, I suggest you do some research because that is everywhere. Talk to a teacher. Or a psychologist, where they call it "depth of processing" (which is a primary determinant of how much of something is incorporated, alongside frequency of exposure). Or just go to a gym and see how many people are getting stronger by paying 24/7 brilliant private weightlifters to do the lifting for them.