Because it's drastically cheaper in an obvious dumping exercise, and has some interesting IP kids and grown ups that used to be kids want to (re)watch. However there really isn't that much content on it, nor is new content coming that quickly, so at some point after everything of interest has been seen, people will start unsubscribing.

This is why Netflix is constantly churning out new stuff of very varying quality (utter shit next to masterpieces) - you need to keep people paying the subscription.