TW dropping charges for what if actions were the same in all cases?

An

I came across this story and I’m highly puzzled. The prosecution says they cannot for sure try the case beyond a shadow of a doubt but if the motives and actions were the same between all victims then how is that possible? Why bring the charges in the first place? The victims have some sort of evidence and testimony.

I’m puzzled. Do you guys think it’s possible that this one case is much stronger than the other 6?