[swiftcoder]

> It's not reasonable to expect the application layer to carefully partition its work into "I/O heavy" and "CPU heavy" parts.

If your application has both of these and doesn't partition them, you already have a fundamental flaw in your application architecture. Every serious piece of software does this, from web GUIs, to servers, all the way to video games.

> It's not reasonable to queue up an arbitrary amount of work without back-pressure

Absolutely, which is why we use pull-futures instead of push-futures, across the entire rust ecosystem. Creating unbounded queues in Tokio requires a fair bit of error on the part of the programmer