Android certainly does have a feature to block screenshots in apps though.
* apps that show sensitive personal info (e.g. credit card numbers, SSN, etc.) should ideally self censor the sensitive info to help prevent accidental leaks
* corporate devices where the phone and all of the data within it belongs to the employer
What's missing is just a user override of "no really screenshot this that wasn't an accident", that's about it.
When it comes to piracy of copyrighted music and movies, the analog hole is deemed to offer a significantly degraded signal and therefore DRM is still effective enough.
When it comes to screenshots, I think a native screenshot and a photo of a screen offer more similarities than differences and therefore it's not worth blocking one without blocking both.