Comment by kllrnohj

The Thunderbolt offerings on the current Mac lineup offer dramatically less bandwidth in total if that matters for a given use case. Thunderbolt 5 is the equivalent of PCI-E Gen 4 x4. So if all 4 of the Thunderbolt 5 ports on a Mac Studio can run at full speed, that's still only the equivalent of a single gen 4 x16 slot. That's less than half the bandwidth of a basic consumer x86 CPU, to say nothing of the Xeon that was in the previous Intel Mac Pro or a modern Epyc/Threadripper (Pro).

This is a big reason why things like eGPUs kinda suck. Thunderbolt is fast for external I/O, but it's quite pathetic compared to internal PCI-E.