Dunno if they meant this, but I feel that adding async to a language/ecosystem where it was earlier not used makes everything awkward for a long time. Especially if it's done liberally like python did, with both sync and async styles still supported.

It feels like the worst of both worlds at times. I think Rust suffers from this too, whereas Node.js has managed to make async the default mode of operation for enough things that it doesn't feel so bad. Especially with Typescript.