|I think in that case, Amazon wants to have its cake and eat it too. Amazon refuses to sell the hardware devices from other companies that also produce video content competing with Amazon's own video offerings.|
Google's Chromecast is not sold on Amazon, yet Amazon's Fire, Stick and others could view Google's YouTube and their new streaming service, YouTube TV.
As mentioned in the article, same was true for Apple's Apple TV (and still is), but supposedly they came to an agreement that would allow Amazon Prime Video on the latest Apple TVs (only the 4 and 4K though, I believe).
Presumably sales of Apple TVs would resume at Amazon when this happens "before the end of the year," but it hasn't occurred yet.