Library authors won't, and I would argue shouldn't, make their code dependent on a particular promises implementation. When/if either ES standards body or Node

Library authors won't, and I would argue shouldn't, make their code dependent on a particular promises implementation. When/if either ES standards body or Node authors choose a method that will become the default. Until then individuals will use the library they like, or none at all, and we've gotten by without promises in the last 10 years that JS has exploded in popularity. By the way, Q can easily wrap node-style callbacks in a single line.