You can't do resource management at compile-time for games that have 50gb of assets. Also, Rust may help with accidental memory leaks, but you still have to deal with things like heap fragmentation.
Interesting point. Normally, your programming language can do little about fragmentation other than requesting a better allocator, if available (Windows?). Makes me think, maybe Rust's model would allow it to plan for better allocation requests? (Not saying Rust does that, just came as an idea.)
The main advantage I see Rust having here is making it a little easier to (ab)use the stack for temporary stuff in a way that can be verified to be safe. Nothing you can't already do in C++ at the expense of the occasional heisenbug.
Games often create their own allocators for a variety of reasons (specialized allocation strategies for speed or fragmentation reasons, adding debug statistics, enforcing memory budgets for (sub)systems, etc.) - although that's not terribly OS or language specific.