XPS 8930: Does anything use the ASMedia USB 3.1 eXtensible Host Controller?

According to USBlyzer utility program my system has one of the above but none of my hard drive connections appear to use it.  It seems everything, all front and back USB 2 and USB 3 ports, uses the INTEL Host Controller.  What is the ASMedia device used for anyway?

It can happen that I get "Insufficient USB Resources to connect this device" error messages if I attach too many hard drives, especially those Seagate Backup+Hub ones with the two built-in USB ports.  The hub ports seem to multiple like rabbits, everywhere, every 4-5 ports a new one branches out from the "tree", layer after layer after layer.

My research suggests that INTEL USB 3.x architecture only supports 96 USB "End Points" per host controller, but that AMD AM4 architecture supports up to 254 such "End Points".  Rather than a new AMD system, I was considering adding a PCIe x4 board with a separate USB 3.x controller for each of its four ports.  Would this alleviate my problem, or am I simply misunderstanding this whole (overly complex?) USB thing?

BIOS option of disabling FRONT or BACK ports, per the service manual, would seem to imply there are two independent USB Host Controllers here but I probably have that overly simplified too.

Thanks,

---JCN