Blizz doesn't force anyone to play there game, if your playing 80 hrs a week as is being thrown about then thats by choice.... and the only person who logs on your char is err you.... any perceived requirements is entirely driven by the guild/raid leaders who run the raids or by the player.
If you choose to play 80hrs a week and burn out, that is entirely down to either you, or your guilds requirements not any requirements set down by Blizz.
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They don't, its entirely player driven.