Question Question about transform.rotation

The documentation for transform.rotation at https://docs.unity3d.com/ScriptReference/Transform-rotation.html
says "Do not attempt to edit/modify rotation".

A few questions about this.
(1) a large percentage of unity tutorials I find on the web do exactly this to rotate an object. Are they doing it wrong?
(2) why is rotation publicly settable then?
(3) the Unity documentation has an example:

Code (CSharp):

1. transform.rotation = Quaternion.Slerp(transform.rotation, target,  Time.deltaTime * smooth);

Isn't that doing what they said not to do?

 

I think it means don't modify its components directly, since it won't behave as it looks in the inspector. But it's fine to modify its value as a Quaternion.