There are also instances in which having your own parser data could help to disprove others.

When I first hit endgame in the 2.0 days as a MNK playing on PS3, I was trying to get my Titan clear. I had looked at rotations and knew the basic fundamentals of my job but I'm not holding any illusions that I was anything above average. In any event, I get into a party for 6/8 or 7/8 from the same FC, who are trying to get a clear for one of their members. The BLM runs underneath Titan everytime he jumps and dies, as such we are fighting with 3/4 DPS the entire time while I didn't get hit by anything. After 3 wipes, they all suddenly drop and then say "MNK has too low DPS" and boot me. I wanted to quit trying at that point but saw another shout and joined that party, determined to try it once more. We ended up one shotting and I was told that my DPS was 'average'.

Basically I was average for a player just entering endgame but I didn't have high enough DPS to overcome the BLM constantly dying. Had I had any indication what my own DPS was from the game, I may not have felt as bad about the way the first party treated me.