I'm sure your way is more efficient, but I was not really focused on the most efficient way to do things when writing this tutorial.

I was interested in demonstrating how to do things in as illustrative and understandable a manner as possible.

I broke it into stages just to illustrate it better, and to prepare for the next article in which I automate the transforms in SSIS.

For me, learning how to do something new is the hard part. Once I understand it, I can figure out how to improve it on my own.