Recently I noticed that Safari 10 for Mac/iOS had achieved 100% support for ES6. With that in mind, I began to look at the browser landscape and see how thorough the support in the other browsers. Also, how does that compare to Babel and its core-js runtime. According to an ES6 compatability table, Chrome, Firefox, and IE Edge have all surpassed what the Babel transpiler can generate in conjunction with runtime polyfills. The Babel/core-js combination achieves 71% support for ES6, which is quite a bit lower than the latest browsers provide.
It made me ask the question, "Do we need to run the babel es2015 preset anymore?", at least if our target audience is using Chrome, Firefox, or Safari.
It's clear that, for now, we can't create a site or application that only serves ES6. That will exclude users of Internet Explorer and various older browsers running on older iOS and Android devices. For example, Safari on iOS 9 has pretty mediocre ES6 support.