Apple has also catered heavily to the professional artist/creative field. Large scale movie editing, massive audio projects, and especially 3D animation or arch vis will definitely leave the Apple ecosystem if they kill the desktop-grade Mac. Workflows in these fields are often pegged to the latest hardware, and the GPU/CPUs in notebooks - not to mention storage, RAM, inputs - aren't often up to the task. Not to mention, these sorts of projects are rarely done "on-the-go" so portability isn't necessary.

Things like visual design, print design, and UX are not very heavy tasks and could all be done without even a dGPU... but the entertainment industry, as far as I know it, has been Mac heavy in the past. Maybe I'm wrong though.

Remote render farms are becoming more affordable, however.