There is little to no way they could ever implement something like this and it not be abused by either trolls or try hard type players who expect absolute perfection. Leveling a healer now, I've come across all variations you could classify as "bad" for one reason or another. Undergeared tanks, LOLgoons pulling for the tank and so forth. I just accept that's the gamble I take with the Duty Finder and try to heal through the extra damage. The best you can hope for is explaining to players what they're doing wrong, hope they listen and if not... suck up the lost time as a bad roll of the dice. Sure, it sucks, but there really isn't a way around it.