It's because their predictions, are in fact, accurate on a large scale. I actually emailed them for historical data about two years ago and its uncanny. Games where they predict the winner of the match is very accurate given a large sample size. I broke it out into ranges of 51-55,56-60, 61-65, 66-70, etc. All of those hold true. Meaning if a team they predicted had a 68% chance of winning it would fall in my range of 66-70% chance.
Long story short the whole point was to find an edge when books set moneylines wrong. You just need a HUGE bank roll to ensure it works.