Where did you see "a major hurdle" written?

You are doing exactly what is being criticized in the Rust community. Bad faith reads of someone who spent significant time getting into the language.

This is missing a few useful ones, like Box<str>, Arc<str>, Cow<'a, str>, SmallVec<u8>, transmuted newtype references like &UserId, and of course the string type you implemented yourself because the previous ones were not good enough.