It's all marketing. Providing new content free of charge isn't something only CD Project does. They simply act like it's revolutionary, and people seem to believe them.
Titanfall players got whole new modes and gameplay mechanics (Black Market) months after release. Burnout Paradise had amazing post-release support even back in 2008 with hundreds of free challenges, cars and even the introduction of bikes. Evolve got new Maps and Modes free of charge. Halo 5 will have free Maps post-release. And those are BIG publishers: EA, 2K, Microsoft.
Difference is. They don't pander to their audience quite as much as CD Project does. CDP know that they are loved - and rightfully so, they are an amazing studio! But with their "Free DLC Campaign" I really felt like they sold something that's slowly becoming an Industry standard like a big, new revolutionary thing only they would ever do because they love their fans so, so much. And the community ate it up because it was another chance to celebrate CDP while shitting on other publishers - even though they were often doing exactly the same thing already. Kind of rubbed me the wrong way, especially because much of it was just "Here, have a new skin/animation".