In ancient days – it was sat yuga then. At that time the number of people who wanted liberation was a lot more.
At that time for the true aspirant they had a system called Gurukool. Children at the age of 5 were sent over to be raised by a teacher. What did he teach ?
The art of mediation.
As time passed by the number of true aspirants dwindled. The gurukul tradition continued and they started teaching them worldly knowledge.
And now the tradition is no more.