Monster Hunter is a social series designed to be played with friends. Monster Hunter: World is no exception, and even added new social elements in the form of post-hunt emblems highlighting what teammates contributed to the hunt—things like most monster parts broken, statuses applied, or slinger shots landed. One of the most coveted emblems is for most damage dealt, which I can only assume inspired modder muriEX to create this mod which not only tracks your overall damage, but also your DPS.
As muriEX explained on Nexus Mods, the DPS overlay mod "displays the damage breakdown and DPS of your current team." During a hunt, you can see how much damage you and your teammates are doing at any given moment. After a hunt, you can see how much damage you and your teammates dealt to the monster relative to its overall health, as well as your average DPS.
World's post-hunt damage emblem shows up very rarely, but many players would like to see their damage after every hunt. There's just something satisfying about knowing how much damage you dealt to a monster, kind of like a post-raid breakdown. MuriEX's mod not only meets that demand, it provides additional information which players could use to improve their play.
However, this mod is also in the gray area of what mods Capcom deems permissible. It's not like the cosmetic mods we've seen crop up, but it also doesn't provide any sort of power benefit. But because Capcom hasn't clarified its policy on mods for World, some players are nervous about modding their game at all. So, as always, mod with caution and at your own risk.