This only works if its optional by opt in, and cannot be forced by random people. So only in a full lobby by a vote that has been accepted by all players. It could even be made part of a FC setting to indicate they demand this feature to be active.
Casual groups wont care about it, and just leave it off that way, but dedicated groups will demand everyone to agree. And in any roulette or matchmade event it never will be active.
To assist a bit towards the player themselve, they could see their values at the end of a dungeon, but obviously cannot compare those to teammates, only their other dungeons. And this isnt realy a very effective way to measure your performance towards others, but can still give some indication. Because dungeons can have varying clearing times depending on your teammates. So these stats might simply just end up being the total values and not value over time. A quite pointless value to me, but im not the one that is going to care much about those stats anyway. For me it simply comes down to: How many attempts did we need to clear it (and if we cleared it).