DRM doesn't "increase the rights" of copyright holders, it just intentionally goes out of its way to stifle everyone else. The fact that it's called "Digital Rights Management" is a bit of doublespeak, which is why the FSF encourages using the more accurate description of "Digital Restrictions Management."

Although it seems the word "copyright" is also a bit of doublespeak these days. In general it doesn't go out of its way to give authors the right to control how publishers distribute copies any more, it's been co-opted as a system for publishers to deny every individual the the ability to make their own copies for any reason. If you ask me they should call it a copy-block instead of a copy-right.