Another thing is the way the rootball developes!
If you start your plant in a large pot, it tends to run the roots down and cover the bottom rather fast - not really using all the pot space very efficiently or evenly. And, like said earlier, the roots aren't able to develope a strong network because they are so "spread out and free to roam".
Keeping a new plant "somewhat confined" in a small pot allows the root to develope a compact, strong, rootball. And incremental repoting allows that "Ball" to grow larger and use all the pot space more efficiently. A stronger, bigger, root system makes a stronger, bigger, grow!