> Even if you use heavyweight OS threads, I just don't believe this matters.

It matters a lot. How many OS threads can you run on 1 machine? With Elixir you can easily run thousands without breaking a sweat. But even if you need only a few agents on one machine, OS thread management is a headache if you have any shared state whatsoever (locks, mutexes, etc.). On Unix you can't even reliably kill dependent processes[1]. All those problems just disappear with Elixir.

[1] https://matklad.github.io/2023/10/11/unix-structured-concurr...