DPS gauges or meters of any kind provide incentive for people to discriminate against eachother based on their current gear, regardless of whether or not it actually matters for a win. Just look at the minimum ilvls in party finder, they're usually a good ten to twenty ilvls higher than they need to be.

The concept might not be inherently bad, but it opens the door for players to be even more discriminatory than they already are, and that should be avoided at all costs, imo.