Macs have "unified memory" meaning the GPU uses the same memory as the CPU and minis can have up to 64 gigs. So its a lot faster than running on a CPU and a lot cheaper than any other GPU based rig with similar memory.

Because these people have Apple IDs, and they need a machine that can access their various accounts.

The Mac mini has a very good value for money if you need raw performance in a small silent package. Frequently available for between $399 - $499 discounted.

A VPS that can perform like a Mac mini will likely cost the same as a Mac mini in 12 months time.

so you can use the full operating system

claws are run mainly by rich american programmers. The only computer they have is a macbook. The only brand they know is apple. The only cloud they know is serverless

In classic Apple fashion, they fooled people into thinking an integrated GPU is the same as Nvidia.

Gosh I wish I could hire their marketing company.