Yes it is not safe. Just because you do not access undefined memory in an untyped GC language like javascript or python does not mean you can enforce that program invariants are maintained. You still get resource leaks, races, corruption etc. just without a crash (which makes it arguably worse because the defect is not immedeately apparent) Encoding program invariants cannot have "correct" solution, because you must balance expressivenes with compile time decidability.

I'm not saying that borrowing protocols are the _only_ way to get memory-safe programs. But aside from that, yes exactly. How memory management in C/C++/... works is not inherently safe, otherwise we wouldn't have all the memory-related bugs we have. Of course, you can write memory-safe code, but adherence to borrowing protocols can guarantee that your code is memory-safe, or at least reduce the risk by a lot.

And you can use `unsafe` in Rust, code up all sorts of memory-unsafe stuff and have it blow up in your face.

In both cases, it should be clear to you that you are behaving in a possibly dangerous manner, that you should know what you're doing and that you are responsible for not endangering others with whatever you're doing.