It's not 'disguised', it's abstracted. launchFiber does what it's name implies: launchs a fiber. How it is achieved 'internally', it's irrelevant as long the abstraction is not leaky.

Today launchFiber is calling the fn inside a Fiber(), tomorrow could be launching the fiber by means of a generator.

The idea was to create a very simple abstraction to avoid callback hell, adding low or no complexity, and keeping the flexibility to use all the existing async fns with a callback or just "wait" for the results.