alt Hacker NewsI don’t think this delineation is that clear, unless by “application” you mean the app tier of a 3 tier app.
Postgres and Nginx make sense in system programming languages; they’re extremely performance sensitive and that granular level of control offers them features. Interpreters are sort of the same, they interact with the OS a ton, it makes sense to work in the same language as the OS.
I do generally agree for the app tier of a web app. I wouldn’t build a CMS in Rust, but I also wouldn’t build a reverse proxy in Python.
Writing an operating system kernel in C is valid usage since there's a great deal of thought going into it and it almost never changes.
EVERYTHING ELSE is invalid usage no matter how performance critical people claim their application is. These are just excuses for people to use a grossly unsafe language to get that last 2% of performance whilst costing the world trillions in lost productivity and security breaches.