I think the main issue with async/await specifically is that it is abstracted away from most developers. I may have a sync program running a main loop and I wa

I think the main issue with async/await specifically is that it is abstracted away from most developers. I may have a sync program running a main loop and I want to have a subset of that program using something like the reactor pattern. In any multithreading aware programming language I can do that by just sticking that in another thread and syncing however I want, even using coroutines I can do that, it doesn't need to follow the reactor pattern. However libraries (tokio) and languages (js) don't make that the obvious default. In something like JS it isn't even possible, the entire language is built on top of coroutines. For tokio the default is "put tokio main here and voila async" and you need to actually understand what it's doing under the hood to know that that isn't the behaviour you want in all cases. This is more bottom-up vs top-down learning. Most people learn and teach top-down because it gets you to productive really quickly. Bottom-up is much harder and has the chance of getting lost in the weeds but makes what is happening very obvious. Does tokio use reactor or coroutines? It depends...