The purpose of DRM is to give content providers leverage against creators of playback devices.
Paramount make a movie. A DVD store buys the rights to distribute this movie from Paramount, and sells DVDs. You buy the DVD, and want to play it. Paramount want you to sit through some ads, so they tell the DVD store to put some ads on the DVD labeled as “unskippable”.
Without DRM, you take the DVD and stick it into a DVD player that ignores “unskippable” labels, and jump straight to the movie.
With DRM, there is no licensed player that can do this, because to create the player you need to get permission from Paramount – or rather, a licensing agent created and supported by content companies, DVD-CCA – otherwise, you are violating some set of patents, anti-circumvention laws, or both.
And a condition of the license is that “unskippable” must be supported.