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> Languages such as Go and Erlang bake support for asynchronous IO directly into the language, while others such as Rust rely on third-party libraries such as Tokio.

This is so wrong. Go and Erlang have message passing, not async. Message passing is its own thing; it should not be mixed with threading or async.

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Go offers channels in the standard library, which you can use to do message passing, certainly (so does Rust). But I/O through the stdlib is absolutely asynchronous. I/O routines that would block, like sending and receiving from the network, are all magic async switch points where your goroutine can be replaced on the current OS thread with another. When epoll (or whatever) signals readiness on the blocked descriptor you get switched back on. As described in the previous post, the asynchronous I/O is hidden from you as an implementation detail of the language but it's absolutely there.

That's in practically every nontrivial language.

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