It is a violation for a CLOSED SOURCE project to link to code in a GPL project, if that linked code is fundementally important, and paramount to the operation and identity of the closed source program
Likewise, a GPL program 'shouldnt' link directly to a closed source library, if the same is true.
ReactOS is capable of booting, displaying an image on the screen, and accepting input from the keyboard and mouse without the need of 3rd party drivers. Thus, ReactOS doesnt have a dependance on any closed source software.
ReactOS, Further, does not provide such software or drivers.
This separation is to protect the intelectual property of both the closed source project, and the GPL project, by preventing their licences from contradicting each other.-- The GPL is explicit in this, but only as for as above---
If the license for the closed source software doesnt care about the target platform it is run on, it is then perfectly legitimate for the end user to run this non-gpl software within ReactOS. In this manner, the end user is allowed to install and use drivers meant for windows OS, if the license agrteement for that driver is not explicit in saying it is ONLY for windows--- Because ReactOS runs and works just fine without those drivers.
ReactOS is being developed to be ABLE to make use of those drivers-- Those drivers are not a requirement for the OS to function, and so, the whole thing is neat and tidy.