Individual training is ideal for gaining knowledge, but ..
First, it is quite expensive and not everyone can afford it.
Years ago, this was true. Since the internet, alot more resources are available that would allow those who can teach themselves to do so. 1-to-1 tuition is still expensive, of course, but self directed learning is not.
The child must understand what life is, that it can be cruel, that there are difficulties. The child must learn to take the fight. He should be able to get out of the conflict, to defend himself, etc.
I think that in order not to break the psyche, parents should support the child and explain important things about relationships between people.
Nowadays, you need to be stress-resistant, you need to be competitive and able to fight. It is necessary to overcome difficulties in communicating with others.
Therefore, it seems to me that individual training no longer meets the requirements of modernity.
I disagree.
In schools, children are forced to let teachers resolve all but the smallest conflicts. That doesn't help kids learn how to solve their own conflicts, as they don't become familiar with the full costs of over-escalating arguments. As a result, too many kids grow into immature adults that are too willing to start anti-social conflicts with others, in the expectation that their future experiences will be the same as those in the past (i.e. teacher will come and deal with it). So, the school system does not socialize such characters, it does the opposite.