- GPU is integrated into the SoC - Surprisingly, it is possible to plug a drive into a TB/USB port
…so what do you actually need PCIe for?
To have lots of them plugged together, high end audio cards, electronics integrations, disks with having cables all over the place.
Things that aren’t graphics cards, such very high bandwidth video capture cards and any other equipment that needs a lot of lanes of PCI data at low latency.
Video capture
I/O expansion
Networking
High-end Macs have moved to PCIe 5.0 speeds in their internal drives. Thunderbolt 5 is not fast enough to get the same performance from external ones.
Thunderbolt is also too slow for higher-end networks. A single port is already insufficient for 100-gigabit speeds.