It depends on what “can be used” means. I really like C# and it “can be used” for that full stack C# for example can write out native machine code, can manually and precisely lay out memory, and can directly link to assembly language routines. You can write an OS in C#. Even as a fan though, I would certainly argue that it is the wrong tool for that job.

In the same vein, while I know C++ “can” be used for web dev, I would argue that anybody that tries to do so for any significant project is insane.

I am not sure I would use Rust for “everything” but I do think the claim that Rust is one of the first languages where it is reasonable or practical to choose it for any of these uses is valid. Rust code can be very high level and often does not much different than a scripting language. At the same time, it can go as low-level as you want. This article is about an OS in Rust ( and there are few ). Web dev in Rust is totally reasonable and there are a few popular frameworks available. Rust has one of the best WASM stories around.