USB Beginner Q: Why PIO instead of USB peripheral?

[breadvsrice]

Just curious. I understood the pico / pico2 includes a TinyUSB stack with capability for both Host/Device.
I'm interested in CDC for transferring more serial data than standard UART->COM can handle.

But why use the PIO for USB when the rp2040/rp2350 includes the USB stack already?
To be fair, I haven't dug around the TinyUSB code yet to see how complicated setting it up would be, but still...