High end VFX/CG usually tessellates geometry down to micropolygon, so you roughly have 1 quad (or two triangles) per pixel in terms of geometry density, so you can often have > 150,000,000 polys in a scene, along with per vertex primvars to control shading, and many textures (which can be paged fairly well with shade on hit).
Using ray tracing pretty much means having all that in memory at once (paging sucks in general of geo and accel structures, it's been tried in the past) so that intersection / traversal is fast.
Doing lookdev on individual assets (i.e. turntables) is one place where GPU rendering can be used as the memory requirements are much smaller, but only if the look you get is identical to the one you get using CPU rendering, which isn't always the case (some of the algorithms are hard to get working correctly on GPUs, i.e. volumetrics).
Renderman (the renderer Pixar use, and create in Seattle) isn't really GPU ready yet (they're attempting to release XPU this year I think).
OTOH, Vfx rendering involves a varying scene with moving light sources, cameras, objects, textures, and physics. Much more dynamic interactions. This is a gross simplification but I hope it helps.