There is a fundamental misunderstanding beneath this question, and many similar questions.
Reality is that when you plug a USB 2 device into a "USB 3 port", you aren't really plugging into a USB 3 port! Not electrically, anyway.
The USB 3 port has all of the pins for a USB 2 port in it. The USB 3 cables have wiring for both. The host controller actually has logic for both USB 2 and USB 3 in it, and enumerates on the host system as two controllers: One USB 2/1.1/1, and one USB 3.
When you plug a USB 2 device into a USB 3 port, the USB 2 device uses the same pins that it always does, and those pins connect to wires that take the connection all the way back to the USB 2 controller int he host. Which does the same things that any other USB 2 controller would, and has the same 480 Mbit/s speed limit.
It is not the case that the hub or whatever takes some of the USB 3 bandwidth and gives it to a USB 2 device if one happens to show up. The controller provides both a USB 3 bus and a USB 2 bus. The USB 2 bus has all the bandwidth available that it usually does, without taking anything from the USB 3 side.
It is also not the case that having USB 3 capabilities implemented in the same controller - even if in the same chip - as the USB 2 controller will make the USB 2 controller work any faster.
So there is no reason from the architecture to expect that a USB 2 device plugged into a USB 3 hub (or port) will work any faster than if it's plugged into a "native" USB 2 port.
As others have suggested, it may be the case that a new USB controller that supports USB 3 as wwell as 2/1.1/1 might be faster at doing USB 2 than an older
USB 2/1.1/1 controller. But it isn't inevitable.