Easy. You show that Samsung spent a zillion dollars trying to make a folding phone and the display still creases. Best way to demonstrate novelty for patentability is to point to an expensive failure to solve the same problem.
Maybe because the option of not folding it so sharply is now under patent, so Samsung didn't have that option.
Moto filed in 2017. These phones have all been in development for longer than that.
This was filed in 2017-05-31, so wouldn't have been published until 2018-12-01 (18 months later). Samsung likely wouldn't have know about it until then.