This is a case of exactly the "hoarder" modality in C++ that I described. When somebody says array in C++ you think of std::array, the newer shiny C++ class which you're asked to use instead of the native array types. The native array types in C++ still exist and indeed do not provide methods like size()

In Rust the arrays aren't stunted left over primitive types which weren't gifted modern features, array.len() works because all Rust's types get features like this, not just the latest and greatest stuff.