Parsers are technically inaccurate due to the way the game is developed anyways isn't it. Like when a multi-hit WS kills a mob, the damage can come up short because each hit is calculated seperately and it only displays the total. So you could average 1000 damage with Asuran fists, kill a mob and only do 400 because only that much damage was needed to kill it and the rest of the hits were ignored.

Then you got other factors which affect damage like when people afk to use the restroom or eat, people soloing their own mobs, players that have other utilities (like stunners, backup healers, backup sleepers), jobs that lack critical based WS's, and people with higher tp gain (not necessarily higher DoT) pulling out bombshell WS's killing a mob before others have a chace to get their own tp.

Just wayyy too many things out there that would mess with results, but thats just me.