Copyright violations would continue to be illegal. I am not proposing that they be legalized (though copyright law could use several reforms as well). I am proposing that for instance Google ought to be required to license Widevine to anyone who wants to build an implementation for it.
Because Widevine is so widespread and acts as a gatekeeper for content (for example Netflix), if Google doesn't bless your platform with Widevine support you're essentially dead as a consumer media platform.
Google should not have this kind of power because competition is good.