The people who say that the "callback haters" hate it because of indentation miss the point.

The problem is readability and flow. async makes code flow (and perhaps more importantly , data flow) harder to grok without knowing the code well. closures don't help with that, but renaming doesn't help either. Especially if your thing is going to be named things like WriteToDiskAfterOtherFileRead or something.

things like yield and whatnot are embraced because it allows us to build things with clearer patterns. Callbacks have their place as well, but when you think about how most people reason about IO (even in async fashion), a better expressive tool would be appreciated.