This would be fantastic. I don't trust 3P add-ons and am a paranoid git. I would love to know how I am improving as I play more with my Summoner.
A self-only parser would not lead to anyone being harassed because you still don't know their DPS numbers. Other than the development cost (and I would hope this is minor since damage/aggro is already being tracked within the game engine) there is literally no down side.