Say you have 4 vertical planes, separate objects and want to use the same style on each. .but then you decide to change that style, using linking will change the style for all.
Example.. create 4 separate rectangular splines. Assign a RC object and a style to one of them.. now create a second RC object, in the scene, go to modify panel and below Mater Style, click on NONE and select the first RC object you created, this will link the second to the first and should you change the first, all others will change along with it.
Hope my explanation helps.