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I'm not here to argue with the ratings, but only to analyze why they are so high.
When a new heavily-hyped game launches, it often has a bunch of people excited to play it who promptly rate it a 10. That spikes the game to the top of this site's ratings for a while. Then as players get further into the game, they find things they don't like, and more people rate it down. That leads the game's rating to drop as time passes.
Additionally, people who don't play a game see it on the top 7 list and rate it down to make room for their own favorite games. Eventually the game drops off of the top 7 list and people mostly stop rating it. That's why there is a huge mass of games that barely miss this site's top 7 list. It also explains why games that not that many people play can easily be just off of the top 7 list, but can't stay on the list for long.
The real question of a game's rating on this site is not of 8.3 versus 7.8 or anything like that. Rather, it's one of, for how long after launch can a game keep its rating far above the pack? With Age of Conan, the answer was about two days. SWTOR and Warhammer made it a little longer than that, but were off the top 7 list within weeks after launch. Atlantica Online actually got a spike and then came back to the pack several times in what looked like a rather flagrant case of ballot box stuffing.
But Rift is nearly two years past launch and still hasn't quite come back to the pack. That's impressive. Some people like Rift and some don't, of course. But those who dislike it deride it as not the game mechanics they want (e.g., it's a theme park), not as a buggy mess of a game.
The Secret World has been out for more than half a year, and Guild Wars 2 for nearly five months, and they're still way ahead of the pack. That's also impressive. Planetside 2, by contrast, is a far more recent release, yet already trails far behind Guild Wars 2 and The Secret World, and will probably soon fall behind Rift in the ratings as well.