I have many fond memories of my first real job as sysadmin/render wrangler for a small animation company about fifteen years ago.
Cores and memory were indeed what mattered, and as long as frames could be fitted into memory then the machine was left to render the frame and then save it back out to shared disk. There was no virtualization, just raw compute hardware running at full capacity 24/7. The scene was already split into different layers and rendered as sequences of frames that were then composited into final products.
First job, first mini-datacenter in a new building, and there I am asking contractors to knock a hole in the building to fit air handlers due to the heat we were expecting to generate. Was great fun.
It taught me a lot about automated systems management.