Comment by dwattttt

In the general case it's absolutely not worth it. In the context of "you want a large number of OS threads, and are willing to go to some effort", it's theoretically something you'd want to do; suppose the startup for a thread is measurably a high water mark for stack usage, after startup the steady state stack usage won't exceed 20% of that high mark, and you'd like as many threads/stacks as possible.

Coroutines / green threads / async tasks will all do this too, but there's something to be said for using/relying on the system scheduler instead of bringing your own in in addition.