1. Async Rust is extra stuff for engineers to learn and maintain in their heads. 2. Async Rust has a lot of papercuts. 3. Very little code actually needs asyn

1. Async Rust is extra stuff for engineers to learn and maintain in their heads. 2. Async Rust has a lot of papercuts. 3. Very little code actually needs async. For example, in an API server, every request handler will need a database connection so the concurrency is limited by the database. I wrote the Servlin HTTP server in async rust, to handle slow clients, but it calls threaded request handlers.