Unless you're doing Savage or some new extreme primal, the game doesn't really punish you for bad DPS rates (except for slower runs, which isn't very noticeable to the person underperforming anyway, unless everyone in the group doing the same). You kill the boss, you roll your loot and your chances of getting an item is the same as everyone else, then you exit/repeat, so you aren't given any motivation or indicator that you should be doing better until you step into Savage etc.

There is the SSS thing, but it seems like only people who are getting into raiding would use it.