VFX studios work with very large assets and UDIM counts ( 1000+ ). Currently Substance Designer only has partial UDIM implimentation and is lacking futher UDIM support to rival its compeditor Mari. This limits Substance Designers ability to do certain tasks required in VFX work.
To make Designer a viable tool choice for node based texture creation in VFX, additional features would need to be added.
Full UDIM visibilty inside the 3D viewport is prio no 1! This is currently a huge blocker
Compositing node graphs treated as texture sets ( 1 node graph applys to multiple udims for a given material or multiple materials )
additional UDIM controls on certain node types such as "bitmap"
A supporting tool set for UDIM workflows such as tile selections, copy/paste/transforms etc.
There is a huge amount of potential to expand on Designers already great ability, but lacking a full UDIM feature set means VFX artists will always default to Mari to utilise its node based toolset.