One is not even a tradeoff* and the other is completely unrelated to having an all async ecosystem. *Anything available in other languages in place of callback

One is not even a tradeoff* and the other is completely unrelated to having an all async ecosystem. *Anything available in other languages in place of callbacks (promises, generators, async await etc) is also available in node. If you are using callbacks you are just ignorant (or don't want to deviate from out of the box features in which case node is the worst possible thing for you). Nowadays there is not even a performance benefit so the only credible reason to use callbacks is not even there.