If one member is doing awesome DPS then ALL the party members are doing MORE DPS than they would have been doing otherwise.
It might seem ironical at first, but this is how it is - The longer the fight the bigger dps loss due to mistakes/reaction time/CDs etc.
Edit:
Btw. The DPS checks are not the issue in Nidhogg Ex. People screwing up mechanics and getting debuffs or eating orbs while having the blue chain are making it seem like the dps checks are the issue.
It requires many mistakes/bad dps players in the group to fail those checks.