It's admittedly a bit link-baity. The async structures in Kal do compile to callbacks in JS.

How exactly are callbacks the best part of JS? Callback aren't a language feature, they're a pattern of doing async code with anonymous functions. Anonymous functions are used for far more than just async code and cannot be replaced with an await keyword which only replaces the need to use callback for async code.

Dont confuse closures with callbacks. Asynchronous non blocking code is the nice thing and callbacks are the price you have to pay to use that in JS,