Earlier quoted context omitted.
What if it's not an independent service, merely a perk of the actual service? Where do we draw the line? Should Apple be asked to spin off iCloud because email, photos, documents should all be independent services? Note that neither Prime Video nor iCloud are monopolies, which would bring different considerations into the matter.
Prime Video isn't a monopoly, but Amazon clearly has Significant Market Power when it comes to retail. They're anti-competitively vertically bundling Prime Video along with retail delivery.
Businesses are allowed to do more than one thing. I'm not sure when it became popular to try to strip down businesses to a single SKU each, and it's not obvious to me that consumers (or anyone) benefits from pursuit of that goal.