Here's a better explanation by somebody smarter than me about why Rust chooses what it does, what else you could choose and what the price is: https://without.boats/blog/why-async-rust/

tl;dr: You can have different (nicer to program) abstractions, but you can't have them in the same language you use to write firmware for a $10 electronic device, or Linux drivers, and we already have languages like Go and Javascript whereas we did not have a safer alternative to C++.