Why don't combined-scale animations and CGAffineTransform translations just work?

Question

Can someone explain why:

UIView.animate(withDuration: 0.333) { self.someView.transform = CGAffineTransform(scaleX: 0.3, y: 0.3).translatedBy(x: 100, y: 100) } 

does not work? The above immediately transfers; only animated scaling.

Also, why does this dirty trick work?

Thanks!