Currently Solus only packages the current stable and some older Nvidia drivers.
This is insufficient for some use cases, for example SteamVR currently requires the current short-lived 387.xx branch
to make use of all features. (See: https://github.com/ValveSoftware/SteamVR-for-Linux/blob/master/README.md )
As well as brand new hardware like the newly announced Titan V graphics card are only supported in said branch.
On other distributions, it would be perfectly reasonable to simply manually install the required driver but for Solus,
the following two issues in combination make that very much unfeasible.
1st) As a rolling release, Solus comes with very frequent Kernel updates, which would require a rebuild of the driver.
2nd) As Solus purposefully and intentionally does not provide DKMS, the rebuilds required due to the above
all have to be made manually.
In combination this means really bothersome manual maintenance for the user, if they decide to use any unpackaged driver.
In this specific case, any carelessness during a system updated could result in a system that fails to boot into a graphical environment
and needs to be recovered.
Packaging the Nvidia beta/short-lived branch would eliminate this issue.