GameObject HideFlags.DontSave not working as expected

Questions & Answers
1

I expected the following MonoBehaviour (tested in a blank project) to cause the GameObject to which it is attached to exist in the scene in the editor but not when the game is played. This does not appear to be how it works, although the manual is not clear on this.

The manual claims that when setting HideFlags.DontSaveInEditor:

“The object will not be saved to the
scene in the editor.”

Can anyone explain to me exactly what effect setting the HideFlags like this DOES have if not what I expected? And how can I go about achieving editor-only GameObjects if not like this?

[ExecuteInEditMode]
public class HideFlagsTester : MonoBehaviour
{
    private void Start()
    {
        this.gameObject.hideFlags = HideFlags.DontSaveInEditor;
    }

    private void Update()
    {
        this.gameObject.hideFlags = HideFlags.DontSaveInEditor;
    }
}
2

Use this instead?

HideFlags.DontSave objects will disappear once you switch scenes.