Why is this movie rated the 16th best of all time?

Rating: 2/10 (5 October 2004)

Why is this movie rated the 16th best of all time, and the all time greatest comedy?
I'd been planning to see this movie for a long time and after checking out the rating here on IMDb, finally decided to rent it. I thought the film to be less than average at best. The acting mediocre, the jokes dated. This could have been so much better - given the subject matter. I realize I'm in a minority here as the percentage of voters giving the film a low score is also low. Am I missing something? Best comedy of all time...tricky one? The Big Labowski maybe?