Rust libraries are infrequently used outside of Rust because if you have the option, you'd just use Rust, not the ancient featureless language intrinsically responsible for 70% of all security issues. C libraries are infrequently used in Rust outside of system libc, for the same reason; I go and toggle the reqwest switch to use rustls every time, because OpenSSL is horrendous. This is also why you say 'rarely' instead of 'never', when a few years ago it was 'never'; a few years from now you'll say 'uncommonly', and so on. The reason C libraries are used is because you don't feel like reimplementing it yourself, and they are there; but that doesn't apply more to C libraries than Rust libraries, and the vast majority of crates.io wouldn't be usefully represented in C anyway, or would take longer to bind to than to rewrite. (No, nobody uses libcurl.) Finally, this only happens in NPM, and the Rust libraries you pull in are all high-quality. So this sounds like a bunch of handwaving about nonsense.