Why waste the time explaining? To be more specific, why waste time COPY-PASTING information they could have gotten by themselves if they actually wanted to?
And the best help they can get is a strong suggestion that they should do some research by themselves, rather than asking for quick recap given them on a silver platter.
If a tank asks something like 'taunt at how many stacks plz?', I never do a pull with him. (example from a pug raid, but same applies to other places)
The person must be able to ask a specific-enough question for him to be eligible for an answer.
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Salvage, CM daily quests (that is why CMs are mandatory for raiders now)... and PvP itemlevel boost creative usage of game mechanics.