I just used the metric from the article:

  > librsvg-2.so (version 2.40.21, C only) - 1408840 bytes
  > librsvg-2.so (version 2.49.3, Rust only) - 9899120 bytes

For your application, I imagine most of your application's code size is in your dependencies -- so if each crate was a separate shared library (for instance) then you'd end up reducing the amount of duplicated code if you had 50 applications that all needed to use RustCrypto.