There are so many things to do in Destiny 2 and so much loot to get. But when it comes to PvP there really isn't much to grind for except loot that you might have a chance at getting. All Destiny 2 needs is ranks like in Overwatch or true ranks from Halo 3. Just something to grind for and have pride in when you get to like Diamond in PvP or earning emblems that shows off your rank