RAII and explicit allocators are independent concerns. That Rust chose a bad default in having 1) a static global allocator, and 2) an expectation of infallible allocations from said global allocator that was then made pervasive in its libstd and third-party ecosystem, has nothing to do with the fact that it has lifetime-based destructors. Having explicit allocators does not mean you need to `free` manually instead of via an automatically-called destructor. A type that allocates needs to ensure a corresponding free in its dtor, and then every other code that uses the type gets the lifetime-based cleanup for free.