Mac Pros are older hardware right now. They haven't really been updated in four years. I've seen rumours that they're coming out with a new one next year.
Side note: I don't feel like the cost comparison is fair, here. A large portion of the cost of the Mac Pro goes towards the design of the thing. Having a small, arguably aesthetically pleasing object on a desk vs even a Mini-ITX case is a no-brainer for a lot of creative folks. The Ryzen PC didn't include the cost of the power supply, case, OS, storage (seriously one of the big selling points of the Mac Pro is the PCIe flash storage)!
The Mac Pro is definitely a failure, it failed to capture the attention of its target market. Why not focus on the real shortcomings? The high cost is only a small part of why that device will probably forever be known as Apple's trash can that should have seen the trash.