The problem with callbacks isn't the indentation. It's that downstream dependent logic has to take place in the callback. If you have two logical branches that

The problem with callbacks isn't the indentation. It's that downstream dependent logic has to take place in the callback. If you have two logical branches that share a downstream, now you have a fork with identical callbacks. So reducing callback indentation comes at the expense of indirection. You're not changing the nesting at all. Usually just brooming stuff under the rug.