Apple has two things going for them: top notch physical quality laptops and macOs. That's really it.
Who cares how shiny a desktop workstation is... ideally you don't even see it. the only reason to buy a desktop from Apple is macOs. And if that doesn't matter to you, why by from apple at all?
And for that matter why buy a desktop from anyone when you can put them together yourself like legos.
"Quiet" is a big one.
The Mac Pro, while insanely quiet for what's inside of it, can't handle high resolution video production and graphics work. The fans peg and heat blasts out the top but the GPUs overheat at 130+ degrees and introduce artifacts into the finished media.
So in the end, the design is flawed. Which is a huge problem now that almost every production camera is 4k or higher now.
Liquid cooling in a PC case is near silent. And the GPU options are more powerful and have the right tools to stay cool. Only you have to put up with Windows which means locking driver versions, scheduling maintenance windows to upgrade edit bays and render machines and working closely with vendors for SAN and 10GbE options so everything keeps working.
It is possible to build a PC or Hackintosh that is as quiet as a Mac Mini.