I don't think it matters what came first. CoffeeScript has had a great effect on hearts, and minds because you can use it. It matters that CoffeeScript exists because people can wrap there head around new concepts and ideas. Only once people really understand an idea can we determine if it's good, or bad.

Fat arrow is well understood in the JS community because of CoffeeScript, and that is one reason why people are pushing for fat arrow to be accepted. I personally think CoffeeScripts has had a very large impact on the idea.