The nanny situation has been acerbated in go here by two things. One is that getting a teacher has become a status symbol, like getting a personal trainer. The other is that too many westerners who fail to become pros peddle their wares as teachers - western-style teachers, unfortunately.
Of course what I say contains contentious elements, but a couple of personal experiences may illustrate why I believe in my view.
One is a friend who studied taiji, at enormous expense, with a Chinese grandmaster. After months of assiduous effort and constant repetition he was admonished by the master: "You wave hands in air. Very pretty. But not taiji." Since the master's English was very limited it was pointless asking what he meant. But my friend is stubborn and he went away and examined everything he was doing. Months later he said he suddenly "got" taiji. He went back to the master and demonstrated his form again. The master looked, nodded and said simply, "Now you go away and practise." Several years later, my friend is now a successful teacher, over 80 but looking under 60. This is using the teacher as a signpost, and not as the map, signpost, and means of conveyance all rolled into one.
The other is more directly my own experience. I played a teaching game on 4 stones with a Chinese pro. Mindful of the ever-present handicap-game commentary that Black must not roll over and play submissively, I attacked from the start. I was pushing her around and, although I lost, I felt that it was just a case of missing a final tesuji, and could/should have won. I was then rather taken aback by her comment: "You were too aggressive. I couldn't get a chance to teach you anything." This was her equivalent of "You wave hands in air. Very pretty. But not weiqi." I likewise went away and re-examined my approach, and I realised, amongst other things, that I had confused naked aggression with attacking. I also had to make myself properly receptive to teaching.
Some while later I played another teaching game with a pro in Korea, also on 4 stones. I now made a concerted effort to apply my new thinking. For that reason it was actually a very tiring struggle and I never felt in any kind of control, even though the pro kept clucking in approval. Towards the end I was so tired I made several bad oversights, and at no point did I feel that with one or two better moves I could have won. I was then utterly astonished when she said she thought I was at least 5-dan, but probably 6-dan. That was so preposterous that I told her so, and she became quite offended at having her professional judgement questioned. In the process of smoothing down ruffled feathers, however, I was able to glean what she meant. It was her equivalent of the nod and "go away and practise". What I had apparently done is to demonstrate to her that I had "got" baduk to a 5- or 6-dan level and so had been able to open the door to a long journey. However, even though a 6-dan (amateur) is sometimes associated with the level of a low-ranked pro, for me to get from 6-dan amateur to 1-dan pro would actually take most of the fabled 10,000 hours - the "go away and practise" bit. It was the difference between grade and rating in its starkest form.
Needless to say I haven't got anywhere near even the first 1,000 hours and never will, but I do feel thoroughly confident that at least I know where that journey would end: I would achieve the ability to play with "no mind" at that level - all the things that I was concentrating on and that exhausted me in that one game would become second nature. Instead, thanks to kgs, I have achieved "mindless" go of another stamp
That is just part of why I believe that arts that have a Way (dao) are best learned in the oriental fashion. To repeat, the onus is on the learner, not the teacher. It is not that a teacher is not needed, but he is mainly a signpost, and the onus is on the learner to prepare himself - tickets, hotels, travel jabs, travellers' cheques - even before he goes to the teacher where, if he clears check-in, he can then continue on the journey by himself to the next signpost.
