That guide is a step by step instruction to have your device with root access, S-OFF and Sim Unlock.
To achieve that you need to complete all the steps mentioned.
Answer:
To have root access on your device, you can stop at the step you've mentioned.
If you want to flash your device, you will need to complete all the steps.
What is root?
Root, in the simplest terms, is the ability for an application to run with permissions that allow it to access everything.
What is S-OFF?
In simplest terms, S-OFF on HTC devices is the ability to flash unsigned code that modifies the kernel, boot, and radio partitions from recovery. Unsigned code is code that has not come from HTC directly, or has been modified in transit.
Having S-OFF does not mean that you have root. Root is a function of a Superuser application.