As someone who hasn't done much c++ in over a decade, but who loves rust, I often find the extreme focus on comparing to c++ to be a bit jarring and unhelpful.

As someone who's worked more with JS/ts/java, I find the borrowing system's guarantees far more interesting wrt concurrency. Yet that's often little more than a footnote in long articles about how rust is safer than c++.

Which guarantees? Rust guarantees there are no data races (like other higher level languages). It does not guarantee anything regarding general race conditions (no language can, at least in a non-trivial way).

Rust gets compared with C++ because that is the target audience. If you don’t need the properties of a systems programming language, you are better off avoiding both C++ and Rust for increased productivity.

It prevents you from sharing non-threadsafe structures between threads. A language like Java provides a concurrent hashmap, but nothing stops you from (incorrectly) using the standard hashmap. Rust will fail to compile if you share a std::HashMap across threads without wrapping it in a mutex or similar synchronisation primitive.