At least with user submitted noisy data you have individual data points, and potential to track individuals over time... unlike the China Study where entire communities were just averaged into a single point.

There's some usable information in the China Study, but not as much as people think... it's being touted as "proof" that all animal-based foods cause cancer (in a popular diet book by the primary investigator Dr. Campbell) because the two were well correlated in the data, when it's nothing of the sort.