I would love one of these if it was a 3.0 hub instead of a 2.0 hub. The idea is fantastic though. I could easily see adding this to my office setup once I get back into my office.
Second this. I can never have enough USB 3 ports. Are they just more expensive?
The issues with this device acting as a USB 3.0 hub were briefly referenced earlier in the thread but to elaborate:
The two main issues are: 1) Power and 2) RF Interference
The power issue is fairly straightforward. If I remember the spec correctly, each USB 3.0 port must be able to supply between 150mA and 900mA of power at 5V. Thus, this device would have to be capable of supplying up to 13.5 watts of power to act as a hub, necessitating an external source of DC power and/or being limited to functioning only when connected to a host device port supporting USB-PD.
The RF interference issue is slightly more complex. There is a known issue with USB 3.0 ports generating interference in the 2.4 GHz ISM band. The OP seems to be averse to the amount of testing that would be required to properly implement an RF shielded USB 3.0 Hub while satisfying the design criterion of "a 3 ports ... USB ... hub intended for wireless keyboard or mouse receivers". There are mitigation methods available which would allow the stated design goal to be realized, but they add cost and implementation complexity.
While it is possible, though poor engineering practice, to simply apply mitigation measures like a fully enclosed receptacle shield and hope they are sufficient, I imagine it would add a not-insignificant cost to have the design properly tested in an RF absorber chamber, likely multiple times during prototyping.
In any case, the RF design considerations necessary to satisfy the original design criterion are non-trivial so I can appreciate the OP's reluctance.
More details on the RF interference issue can be found here, among other places:
https://www.intel.com/content/www/us/en/products/docs/io/universal-serial-bus/usb3-frequency-interference-paper.htmlEdit: Added a missing preposition.