They're using like 20-some 3rd parties to deliver the Horizon experience. Horizon is not proprietary to Liberty, it's a amalgamation of technology from many different vendors.
This is the crux of the issue that cable companies face - they are not hardware/software/UI developers and thus, must rely on many third parties to deliver an advanced-TV experience which, naturally, results in design-related chaos, hence the Horizon problems.
I would suggest reading this article which validates my opinion...