>>1696807It's because it is easy. Anyone can take 2D line art, take ten minutes processing it for a cheap 2- or 3-axis mill, and start cutting metal right away.
The extra effort of learning how to 3D model, how to operate a multi-axis mill, and the high cost of this kind of equipment makes it not worth the investment if you aren't raking in fat dosh as aeronautical engineering or whatever.