That's what a scratch disk is for

I'm not sure a Mac Pro is the best use-case for Lightroom users, if you're working on something that requires that kind of speed/power you're probably on something like Photo Mechanic Plus and/or Capture One Pro.

Lightroom allows to move the cache on another drive...

Besides, perhaps you're the user that needs the multi-TB version. Others, e.g. video professionals wont have huge tens-of-TB source files in their main system drive.

I guess the point is for $6000 it should have another drive.

It should, but with a 24MP camera you can create ~50GBs of compressed RAW files per session pretty easily so, a TB of storage won’t do.

If you add a high performance spinning disk its performance won’t be enough and it will be noisy even when idle.

In the end, it’s better to not add anything and let professionals bring their own storage into the mix.

At the end of the day this won’t be sold to new beginners with no files. The buyers will have their resilient storage and the internal drive won’t be used much anyway.

Unless it’s configured as a developer workstation, but it’s generally MacBook Pro’s role.

Among other things it has, it has a special video decoding card. Some of those in the market go for $3000-$5000 alone.

So I'm a web dev but in a previous role we bought a 2 man company that made medical renders. I ended up making them a mini-SAS Raid 5 made out of SSDs. This is before M.2 started taking off. That thing did 1.1 Gigabyte/sec write on a little table top with terabytes of storage. It was over 20x more than they were used to.