Because debugging better languages affords you more context and more tooling.
Elm's debugger lets you step forwards and backwards in the application's state.
TypeScript's type system lets you catch bugs before you run the code.
Vue.js's DevTools extend the browser's with a component-based overview, so you can interactively see what's going on at a high level of abstraction. (I'm sure something similar exists for most frameworks similar to Vue.js, and possibly even frameworks made in vanilla ES5, I'm just picking one I've tried.)
As easy, certainly. But how are they easier?