>>11590132Pretty much just difficult and costly. Why spend money on mouth movements with 200 different variations and have to link up each crease on the mouth which will take days to do when you can just have a hole that open and closes.
Although I've noticed roberu's mouth looks really good, his mouth model actually tracks when he closes his mouth for the P,B and M sounds, the mouth narrows and widens according to what he says and not just becomes a larger and smaller hole when he talks and this dude talks fast but the mouth model manages to keep up so it flows really nicely. 80% of his content are zatsudans so maybe he paid more for it to be good. Idk im just autistic about the small details im sorry