What are the real advantages that D offers in multithreading?

[Kagamin via Digitalmars-d]

On Wednesday, 27 January 2016 at 17:30:28 UTC, Brad Anderson 
wrote:
> Yeah, boost can do fibers. ASIO has clever/hacky "stackless 
> coroutines" and C++17 is going to add "stackless resumable 
> functions" for async/await. D is about to lose a competitive 
> advantage here.

Isn't asio based on fibers just like vibe?