I just can't really fathom what sort of user needs this much (supposed) power today but is willing to have it locked down unable to add more power at a later date.

To be clear, although this is a seven year-old, cheese-grater Mac Pro, the GPU is new, and is clocked higher than the one in the iMac Pro.

It's just not a professional solution. I'm not sure who would buy one. It's just a stopgap until the Mac Pro is released.