There is another side of this story. Let's say you have to publish content on your website. You do not have any way to publish it as securely as "Amazon Prime" without signing an agreement with Google and Microsoft.
Thirdly, there comes DRM protection rules thanks to team MPAA. In most countries, you can not try to reverse-engineer the proprietary decryption module that comes with browsers without breaking laws.
Because of the above restriction, security professionals cannot break into the proprietary module to detect security vulnerabilities.
Edit: I was wrong about Opera. Opera is in on the DRM bandwagaon for a long time. https://blogs.opera.com/desktop/2015/07/opera-developer-32-0...
It's not just about movies or music, but also about text pages.
Big content has now managed to co-opt the open web. It is no longer a network of peers (some bigger, some smaller) but introduces two tiers, owners and users, and all the power disparity that comes with that.