Roku doesn't build the apps. Just like Apple doesn't build apps for Apple TV, and Amazon doesn't build Fire TV apps, and Google doesn't build the Google/Android TV apps.
If the service doesn't build an app for a platform, then the service doesn't have an app for the platform, whether Roku or anything else. Roku isn't stopping them, they just haven't built one. Fuss at them. They're responsible for there not being one.
Roku Community Streaming Expert
Note: I am not a Roku employee.
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