I’m glad you’ve come to agree to this view that sidewalk is indeed about intended usage - i.e. surface designated to movement of pedestrians! Right? Because, previously, you seemed to have hold opposite stance:
So, you have heard the arguments and changed opinion, right? I have great respect for that! 
Or perhaps you haven’t changed the opinion, and is there some nuance here that I’m missing (i.e. “intended usage to move pedestrians” is somehow different from “activity of pedestrians moving”)?