The author seems clearly inexperienced with Rust (see the paragraph about unwraps and panics) and unfamiliar with common paradigms and ways of doing things in low-level Rust; it's unclear why this post is gaining so much attention on hn. Rust is no worse than C/C++ in writing all sorts of low level codecs, be it with or without using unsafe, with performance matching that of C/C++ and readability/safety usually being much better.

// personal experience: participated in Rust core lib float parser implementation, part of which involved porting it directly from c++; implemented safe rust qoi image encoder, bpe text encoder, etc; in all cases they turned out to be the fastest existent out there; in all cases, though, good prior experience with low-level rust was required, especially if doing it without unsafe and trying to avoid most bound checks, so there's that.