I'm reminded of an ancient 8031 C compiler. It didn't support reentrancy. Which seems like a bad thing until you realize that the program could be analyzed as a acyclic graph. The compiler then statically allocated and packed variables based on the call tree. Programs used tiny amounts of memory.

Given the problems people have with Rust and the borrow checker, I would guess that people will not accurately predict how long an allocation will live (it's a similar issue with profiling---programmers usually guess wrong about where the time is being spent).