This only works for projects which do not involve any R&D, but have a complete and well written functional specification written in advance. Also for projects which do a complete re-implementation of some pre-existing software.
For greenfield projects which require substantial amount of R&D, it’s impossible to architect programs ahead of time. At the start of the development, people only have a wishlist. Architecture comes later, after several prototypes implemented and evaluated, and people have some general understanding what does and doesn’t work, and what specifically needs to be done.
Rust implies that upfront architecture costs even for prototypes.
Just because an algorithm is not representable in safe rust doesn’t mean it’s a bad idea. See my other comment in this topic https://news.ycombinator.com/item?id=42164582 You’ll find similar parallel algorithms in all high-performance BLAS libraries. On my day job I sometimes do similar things in C++, using OpenMP or other thread pool for parallelism.
I don’t like that balance.
For performance-critical things like BLAS and other low-level numerical stuff, C++ is safer than unsafe Rust because standard library and tooling (debug heap, debug allocators, ASAN, etc.) evolved for decades making the language usable despite the unsafety. Another thing, for numerical code you probably need SIMD intrinsics. They were defined by Intel, documentation and other learning resources almost exclusively target C language; C++ got them for free due to compatibility.
For high-level pieces which are not that performance critical, I use C#. Due to VM, it’s safer than Rust. Due to GC and other design choices usability is way better than Rust, e.g. in C# asynchronous I/O is almost trivial with async/await. The runtime is cross-platform, I have shipped production-quality embedded ARM Linux applications built mostly with C#. Unlike Java, it’s easy to consume unmanaged C++ DLLs using C API, or even C++ API: see that library to do that on Linux which doesn’t have COM interop in the runtime https://github.com/Const-me/ComLightInterop