I don't really see this as confilicting information. I do think you have to use some common sense in this matter. I don't think there is only one way to view and present images. The white border may or may not be appropriate. Here is part of my argument....
If I were displaying my images on a while wall as in a photo gallery, I do use a "slightly off-white" background in photoshop (actually, I change the canvas size and have a fill colour of 240,240,240). This gives a very good visual approximation to how a viewer would see the image and sort of shows if you have a good tone range for gallery display.
If I am putting the images in my study (which happens to have cedar walls) or if I am selling an image to a client, I have the photoshop background set to RGB 50,50,50.
If I am printing an image for my monthly print club (which uses overly bright viewing lamps), I tend to print darker - and then, since I know the horrid viewing conditions, I don't really care about the photoshop background.
In other words, nothing is cast in stone - not even book written by experts. They provide good direction - however, you have to be able to interpret their word in "the manner they intended" - which is really tough unless you are also an "expert".