Every major browser ships this already. In Firefox you can choose not to download it, but in the rest it is always there I believe. The reason it was implement

Every major browser ships this already. In Firefox you can choose not to download it, but in the rest it is always there I believe. The reason it was implemented is that Microsoft and Google both also make and sell the DRM systems that EME requires, so they of course shipped it first. It's hard to compete against a browser that works with Netflix when yours doesn't, so everyone else shipped it too.