Most of the complexity of C++ comes from its long history, with new features layered on old, extra junk you have to say to get the new stuff, and old stuff to stay clear of. E.g., constructors should be explicit, and lots of things should be const, and you have to call std::move() to pass a value that way, and implicit conversions can happen accidentally. But actually using it, sticking to the modern bits, doesn't depend on much in the way of new concepts. Writing libraries for general use depends on deep lore, but that doesn't leak out to users of the libraries, who just get libraries that can do more for them.
In Rust, you need to learn a whole new regime to do even basic things. And, you need to learn workarounds for what C++ does but Rust doesn't, yet. There are literally thousands of times as many people who can answer questions about C++ than about Rust, so mysteries are shallower.
