Well, I agree on SE not wanting group dps parsers, because they will be used more for harassing than for other purposes.
But I think if your client show just your own dps, does not hurts anybody, and helps me decide which rotation more effective when I'm in dubt.

Then, about "slacking" dps, I can write books on that. But the essential is when you PUG and the dps of overall group is not enough, you will notice it and then it is your choose if keep on the group or leave the group. Enter a PUG and then pretend to kick out bad apples and keep in the good players is quite nonsense. PUGs are give or take. You will make selection on premades.