alt Hacker NewsA non-linear cost for a small fraction of the phone. A slightly larger PCB with two more layers is about twice the price for the PCB, more antennas is a couple dollars, a one lane PCIe switch is a few dollars if that's cheaper than upgrading your SOC. And if it shrinks your battery 10% you save money on that part.
I blame niche-ness far more than the actual design and production costs.
Edit: fixed the pcb wording
> PCIe switch is a few dollars if that's cheaper than upgrading your SOC
perhaps you're more familiar with these options than I am, but I see 4 lane PCIe switches are 10x10 mm and maybe they are a few dollars but take more board space, new/larger power supplies, etc so it seems that the costs are more than just a few dollar PCIe switch chip. not sure how many phone PCBs can handle additional 100 mm2 but definitely looking forward to learning more.
[1] https://www.diodes.com/products/connectivity/pcie-packet-swi...
add to the antennas are likely based on best/cheapest efficiency for the available area, then additional antenna would reduce the area for each and require more effort/cost.