SE's most difinitive statement yet on parsers

[Reynhart]

Will you still think parsing is cheating when a player makes an addon that does it once the API for addons is implemented?

"Parsing" is not cheating. 3rd party program is. Good to know you don't understand the difference.
And IF they implement it, Yoshi mentionned that it wouldn't be available in dungeons or raids specifically to avoid people from...hmmm..."helping" each other.

So if someone in your group was holding the group back and refused to listen to any advice or anything, say a tank who doesn't use flash for aoe situations or something similar.

You compare people that don't know how to tank well to people that don't have the stuff that suits you. Basically you'd take a moron with a relic over the best player using Garuda weapon.
Exactly how people would kick you for joining Titan HM without a relic even before lauching the Duty Finder back in the days.

And about your little semantic loophole about "cheating", here's a glimpse of the user agreement:
2.1 Cheating and Botting. You may not create or use any unauthorized cheats, bots, automation software, hacks, mods or any other unauthorized software or hardware designed to modify the Game and gameplay. In addition, you may not take advantage of game system bugs and exploits during gameplay.