There isn't any alternative as long there is player greed/selfishness or peer pressure. The abuse comes from losing/getting rewards, including grades itself is a reward. When you see potd ranking, you also compare how much damage others do on the same floor. It doesn't take much for sponsors to do such competition whether using numbers, grades or even sorting by your name. Funny thing about rank/grades, my ig spouse was frustrated that she always come at bottom in the pvp ladder, I had to explain it's sorted by name by default. The neutral thing to do is to have practice runs with no rewards, this should be a thing. Time itself is a good measuring. Practice mode in Raid Finder currently only separates people who already get or haven't get their weekly loot.