A lot of common POSIX functionality is not missing though. I was able to write ripgrep, for example, by almost entirely sticking to the standard library. (I think the only place I reach out to `libc` directly is to get the hostname of the current system for rendering hyperlinks in your terminal.)
We also came at the standard library with a cross platform mentality that included non-POSIX platforms like Windows. You want to be careful not to design APIs that are too specific to POSIX. So it falls under the same reasoning I explained above: everything that goes into std is treated as if it will be there forever. So when we add things to std, we absolutely consider whether the risk of us getting the API wrong is outweighed by the benefit of the API being in std in the first place. And we absolutely factor "the ease of using crates via Cargo" into this calculus.
I peeked at the code for gethostname in ripgrep, and it's nice and straightforward.
Much like op said here; we have a culture of "don't write unsafe code under any circumstance", and we then pull in a dependency tree for a single function that's relatively safe to contain. It solves the problem quickly, but at a higher price.
BTW, thanks for ripgrep. I don't actually use it, but I've read through different portions of the code over recent months and it's some very clean and easy to understand code. Definitely a good influence.
I don't think you should treat unsafe code as that level of toxic. It's necessary when interfacing with with system APIs. The important part is that you try to have safe wrappers around the unsafe calls and that you document why the way you're using them is safe.
We also came at the standard library with a cross platform mentality that included non-POSIX platforms like Windows. You want to be careful not to design APIs that are too specific to POSIX. So it falls under the same reasoning I explained above: everything that goes into std is treated as if it will be there forever. So when we add things to std, we absolutely consider whether the risk of us getting the API wrong is outweighed by the benefit of the API being in std in the first place. And we absolutely factor "the ease of using crates via Cargo" into this calculus.