Pretty tiny domains, though.
Honestly, those are the only professional use-cases for multiple GPUs I'm aware of. CAD uses GPUs, but not multiple and I don't see AMD having any lead over Nvidia. Same with other uses like GPU acceleration in things like Photoshop or video editing--1 decently fast consumer grade GPU is enough. I don't see farms and 4+ cards per box.
Adobe Media Encoder (and by extension Premiere and AE) can do multi-GPU rendering as well, which starts to matter when you have huge comps. I've worked with 2D animators who need to turn around footage really quickly and a bunch of them are on multi-GPU rigs.
Adobe Media Encoder does seem to support OpenCL and CUDA, but the GPU acceleration only looks like it works with certain transforms and filters, not with encoding. So I can see it helping 2d animators, but much less so for video editors--especially with multiple GPUs.
I feel like GPU rendering has been teased for like 10+ years now. Only within the past few years am I seeing studios upgrade their render farm in earnest to accommodate GPUs.
nVidia coasted on having been used in some of the mac hardware thus having access to at least some versions of the APIs, but it seems that what they have no longer works with Mojave.