Because the language's resource allocation style is not so much a "cross-cutting concern" as something which is all-pervasive across every single non-trivial program written in that language. For a long time, we had four styles: Static allocation, purely manual management of dynamic resources, garbage collection (usually with manual management of some resources), and "don't worry about it" for truly high-level declarative languages. RAII adds something to this, but C++ didn't give up new and delete (or malloc and free... or anything whatsoever) so it isn't really a wholly new paradigm. Rust, however, adds something that's genuinely new to most programmers, and it requires a re-working of the thought-styles, so it's worth thinking about whether it's worth it.