Excellent, parsers are now bannable

[Niwashi]

Sure you can measure dps by seeing how fast the encounter goes but there are twice as many dps as there are tanks or healers so their performance are not as easily estimated.

But that is the part of their performance that matters to the game. If the mobs are dropping, the DPS are doing their jobs. If party members are not dropping, then the tank and healer are doing their jobs. Effectiveness is seen in the game itself, not by some number a parser could spit out. Parsers are just a distraction from the more important and useful measures of players' effectiveness.

if using a parser is bannable offense than Yoshi p would have said using a parser, even when no one knows that you're using a parser, will get you banned.

There's a difference between breaking the rules and getting caught breaking the rules. Using a parser is against the rules regardless of whether you say anything about it or not, but SE has no way of punishing someone for a violation unless they know about it. The only way they'll know that you're breaking this particular rule is if you tell people that you are, so that's the only time the rule becomes enforceable.