Often, beginners aren't interested in the process that a more experienced person uses. Beginners want to see a bonsai, not a shrub in a growing pot for three years.
So the books give advice to the person most likely to buy it... beginners.
There is no best way, but certainly many people on this site would recommend that you purchase a tree old enough to have some character in the trunk (5 - 10 years would be better than just a few years old) Prune it back and put it into the ground. You will see the best growth in the second and third years that it is in the ground... once the roots really get established. Keep it fed, trim it when it gets out of hand, and let that trunk grow. My favorite books for this method are Peter Adams books. He shows how to grow and trim.
The pot is last... in fact, we choose the pot based on the final look of the tree. Most of us are too impatient for that, but the point is that the pot hinders growth. Restricting the root growth, and causing larger swings in temperature and moisture, a bonsai pot is actually our worst enemy sometimes. Trees that would be vigorous in the ground, a nursery can, or a growing box suddenly are on the edge of survival in a pot.
Beginners need to go through the stage where everything has to be in a pot... then, as they learn more about bonsai, they learn to relax and work with the pre-bonsai in a more reasonable manner. Eventually they realize that they have more trees out of bonsai pots, and they finally understand that putting the bonsai in a pot is like framing a painting.... you don't do that until the painting is finished.
Joanie