That was my understanding. I suppose the other things that would use the PCIe slots is tasks requiring churning through massive datasets, maybe ingesting media like raw audio and video feeds, maybe science/research. Things where just getting the data in and out of the computer is more limiting than the actual processing of the data.

I think that’s a pretty tiny market, but Apple wants to keep it going as much to say they have one of the most powerful desktop computers available as the actual economics.