This recommendation usually applies to fix issues where a non-powered HUB was used, because non-powered HUBs increase the chances for situations where not enough power is provided to all the attached devices.
In general, it is best to attach the eLicenser directly to the main board’s root HUB (i.e. directly to one of the computer’s USB slots), but this is not always possible.
Best alternative is to use an externally powered HUB.
Worst alternative is to use a non-powered HUB.
Having said that, there are many USB devices, USB HUBs, USB controllers and USB drivers out there; and some combinations of hardware and software will cause trouble, as experience has shown every now and then.
So, the recommendation given above is just meant as an indication to decrease chances for incompatibilities.
But it is absolutely possibly to have a potentially “problematic” setup that is working fine 100%, as well as it is possible to have a recommended setup that still exposes rare incompatibilities.