Except in that scenario you absolutely don't want green threads but real threads. M:N threading (especially if N=1) doesn't help you get parallelism, and parall

Except in that scenario you absolutely don't want green threads but real threads. M:N threading (especially if N=1) doesn't help you get parallelism, and parallelism is what you need for modern CPUs. So that again keeps green threads (and thus mass concurrency without parallelism) in the niche category.