[steveklabnik]

Async engines are one of the worst things you could have chosen as an example. They are wide and varied, with a ton of different tradeoffs for different scenarios. Ones for high performance networking are also complex, requiring tremendous engineering effort, and are massive. Putting something in the stdlib doesn’t magically make something better maintained.

Interfaces also do not magically become good or useful. There has been suggestions around some async traits, but no suitable one has actually been found yet. Yes, it has been a very long time, but that’s just how it goes sometimes.