I’ve had the same reaction. We’ve seen this play out in other language eco-systems (Java - JAXP, javax.validation, JPA, etc all ended up with a de facto single implementation) and the idea of pluggable implementations sounds appealing but rarely pays off. The price that Rust paid for this abstraction - which in fact ended up not being useful as tokio is the only reasonable choice - was high in terms of requiring ugly (to my eyes) changes to its type system.