[monix]

I think you're confusing concurrency with parallelism. Indeed, when these two are combined in the same process with multiple threads sharing memory or other resources, you're effectively juggling with knives.

But in fact concurrency is inevitable in absence of OS threads that can be blocked (another potential clusterfuck) or of some form of continuations support, because it is a direct consequence of asynchrony.

And asynchrony isn't avoidable, all you can do is to find abstractions that make it more deterministic.