How having bit of your desktop showing on the sides any different than whatever background image or color a particular website decides to show on each side of t

How having bit of your desktop showing on the sides any different than whatever background image or color a particular website decides to show on each side of the text? I prefer having a quiet single color background and being able to dictate how wide is the text I am reading than being limited by the website owner's choice. But that is also maybe just me.