That player that hit level 80 in 27 hours spent months in the WOLTK beta planning out the best way to do that and had an out of party pocket priest healing him through the entire experience. He got full experience, the priest got nothing.

Did you read the interview with the guy? He had a team of 5 people that he thanked for helping him powerlevel. XD So, in reality, it took him 3-5 months or so to clear the content, if you give all the prep time.

Naxx (the first raid) is SUPPOSE to be easy. It's meant to be taken as an instance that allows 10 or 25 people into it rather than 5. It's more like a booster seat for new raiders to get use to working with lots of people and to practice synergy.

If you look at the in game achievments, it's not in completing Naxx. It's completing the 25 man version with 20 people or less. ^__^

In fact, all of the entry level raid content (which is all that is out right now) has quirks for the hardcores to go after. You get better loot the LESS trash you kill in one raid (attacking the boss and the trash all at the same time). Blizzard made the raids easy for the casuals (though Uldar is suppose to be very hard and will be released in a few months). And it also gave incentive to the hardcores by offering better loot when they do incredable things like leaving lots of adds with the boss or bringing far less people than suggested.

That said, some people like to rush. I'm a casual gamer. My druid is level 74. My priest is almost level 71. I play about 2 hours a night, though I will admit to playing most of the weekend. ^__^