Series Damping Resistor for Low-Speed USB
I think it applies both to low-speed and full-speed. Because usually, a USB 1.1 controller should support both low-speed and full-speed mode. And in device enumeration stage, we will work at low-speed mode, we can't change the termination resistor dynamically. So, if the termination resistor is not must have ones in low speed, it should work with them. But without it, your full-speed may won't work.