I think there will probably be a lot of objection to this idea, because this is apparently supposed to be a question-and-answer site rather than a tutoring site. But the fact is that it can be and is used for something more in the style of tutoring, and this is something I would like to see a lot more of, because I only participate here in the hope of helping people (and very occasionally getting some help myself) and it saddens me that so much of what goes on here is probably very far from helpful to the people asking questions.
I strongly support the idea of such a tag (I'm not quite sure what the best name for it is - 'tutoring' could sound a little as if it might be for questions about how to tutor maths, and it seems we can't expect people to read the tag wiki).
How I envision it working is that it would be used by people who specifically want to be guided towards a solution rather than having it handed to them all in one go. Ideally we would be able to somehow make it very clear that it is unacceptable to simply provide an answer to a question with this tag. It would also be nice for the sake of those who care about reputation$^*$ if people would vote on answers to questions with this tag based on the entire interaction rather than just the body of the initial answer.
Answering a question in more of a 'tutoring' style can take more thought and time-commitment than even a long 'straight answer', so I suppose it'd be nice to have this sort of interaction appreciated more.
This style of answering my also result in a final answer by the OP, and it'd be nice for this to receive some upvotes as well if it's correct, even if it may not be as well-written as most answers on this site.
This is far from a perfect solution to the "curtailing of students' potential" Rustyn has expressed concern about, since this tag would be used completely voluntarily by the asker. But it would at least help us not to rob a student of the greater learning opportunity of coming to the answer partially by themselves when they specifically don't want this to happen.
$^*$(I don't, although I do somewhat mind unexplained downvotes.)