Well promises help. And then they stop :). Stop helping. They just break under the weight. If you have promise chain that gets too long, you will feel the pain.

The whole thing is, when some IO returns 1 or 2. And your next step is to do a or b depending on the reply. How is your neat promise chain looking now? Then repeat 100 times :(

Not even mentioning error handling... and stack traces.

So i do agree that it depends what you do a lot. Maybe there are domains where it is not important... but i still need to see that one.

And i will take blocking IO with try/catch 10 times out of 10. Even when it is not critical. It is just nicer and easier to reason about.