So, I hate to open up this can of worms again, but....

[Aezelas]

How would it cause problems, may I ask? A personal one could simply be used to evaluate and improve yourself

People would come up with party rules, like ask everyone to post their result in chat.
Low result: you're kicked.
Refuse to answer, because it's meant to be a "personal" parser: you're kicked.

[Fendred]

People would come up with party rules, like ask everyone to post their result in chat.
Low result: you're kicked.
Refuse to answer, because it's meant to be a "personal" parser: you're kicked.

For every bad team that uses it as an excuse to kick people there will be ten that will use it to help their friend get better. The development team can't copy paste the good of WoW without the bad. If they want challenging enrage mechanics, they need parsers.