LR3, Kelby and cropping

Hello,
I have been using both Kelby's and Evening books to learn LR3.
Kelby's workflow and 7-point system do not include cropping as any of the steps.

And this is where I am a bit confused.

Should not the photo be worked on only after it is cropped (if cropping is needed)?

For one , histogram changes after cropping as it only relates to cropped part.

Is my reasoning faulty? Why is cropping not the first part of the workflow?
Rgds