I fail to understand this "discrimination" issue.

There is already a "discrimination" system in place, by the game itself - the ilvl requirement. That is the same as the old "gearscore", and is, in fact, the dumbest kind of discrimination ever.

ilvl is just nominal - you might be an ilvl 100 playing so bad that an ilvl 70 guy can outdps you. On the other hand, an objective "dps value" would be a way more precise measure of a player's skill.
Still "discrimination", sure - but at least a reasonable one.

By the way, I think we should stop using the word "discrimination" to describe "wanting other people to carry their weight", because this is how it's being used.