First, no one is saying the data doesn't exist. It exists, but no one is going to go on a public message board, and provide it.
Second, there is plenty to support the fact as it is being presented. Take the lack of a FP/Line skip option as support that the utilization of the attractions were so poor, that WDW didn't feel it was able to monetize it. Take the fact that WDW is deciding to expend a significant portion of its budget to replace these attractions, as opposed to saving money and keeping something people are using. Take the size of the raft that would bring people over to TSI, the amount of time it takes for a trip to the island, and you get a utilization per hour that is extremely low, and that's without the fact that lines were forming to take the trip over and many time rafts weren't leaving fully packed. Circumstantial evidence is still viable evidence. We send people to prison based upon it all the time.