It's useful, but systems programming languages shouldn't be used to create applications in the first place.
We're trying to solve a problem that shouldn't be solved. We're continuing and even confirming the usage of systems programming languages for application development.
What are the requirements and design constraints of an application? Please give a general answer that applies to all applications.
Rust is also a great language for app code. I reach for it now in places I used to use python.
why shouldn't they? humanity consumes more resources than is sustainable, and systems languages can help to reduce resource consumption.
I 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.