And are you surprised? After all, Macs have their own bespoke GPUs now, and RAM is on-die. (Glad I sprang for the 16MB option on my M1 Air — that has greatly lengthened its useful service life.) If Apple isn't shipping computers with DIMM slots anymore, then why would they ship PCIe slots for anything else? It wasn't like there were many options you could put in the last iteration anyway, because it too had a non-upgradeable GPU and fixed RAM. Okay, okay, you could stick a whole bunch of NVMe sticks in it and it had good cooling. Was that worth it?
This marks the end of the venerable tower Macs that we loved in the PowerPC days. The Mac Studio is the new Mac Pro. We were always at war with Eastasia.