I'm just struggling to figure out how many people actually need the PCIe lanes for anything more than GPUs and storage, though.

Like, what are you actually connecting your desktop to?

The only reason laptops depend on Thunderbolt is because they have limited internal expansion and need high performance external I/O.

If you need more things than gaming boards offer then obviously you have very advanced needs and can go pay for a workstation board, something like an sTR5 socket Threadripper board.