Twitch already rolled out their own ContentID-styled system, pre-acquisition.
Pre-acquisition announcement! The timing of the two is so similar I think it's beyond likely that the anti-copyright protection wasn't a part of the negotiations.
Amazon is in the music and video industry. Twitch already has content ID. Amazon is pretty much Google-level evil plus sweatshops.
While Amazon may not have a YouTube competitor, they certainly have a consumer video product in Amazon Prime Video.