Yeah. $6000 for a computer with a 256GB SSD seems on the excessive side for photography. I'm sure some will rationalize it though. I guess if you have already splashed $50,000 for a IQ4150, what's another $10,000 or so.
It is probably overkill for an owner/operator kind of shop, but it wouldn't be if you spent all day retouching or doing catalogue work.
You wouldn't run that from local storage, so the dual 10Gb Ethernet will come-in handy.
The $6,000 configuration is confusing a lot of people. Nobody will buy it like that, just like nobody ever buys a pickup truck with no options. You will either add more CPU, or more memory, or more storage, or more GPU, etc, depending on your requirements.
I'm not a Mac person, but I ordered a new Linux workstation a few months back. The process was exactly the same (as was the price). Vendors start with a "base" configuration that does nothing particularly well, and then you upgrade the CPU, GPU, memory, etc, until you get what you want. In my case, I knew that GPU memory was critical (for video work), but CPU wasn't. On-board storage wasn't critical either. I run everything off-of a NAS.