AFAIK, Hybris isn't just for the GPU and is used to port various binary Android drivers to ubuntu touch, sailfish, tizen, luneos etc as can be seen from the following chart:
Yes, it can be used any time there is a need for blob that depends on bionic and there is no open replacement. May be for touchscreen driver in this case? That's why it's such a mess with Android only hardware.
No idea why Tizen needs it though. Samsung can afford writing normal drivers for all their hardware.
