Most problems have speed/memory/disk tradeoffs available. Simple coding strategies include "if RAM then do the fast thing, else do the slightly slower thing", "if RAM then allocate that way, else use mmap", "if RAM then continue, else notify operator without throwing away all their work", ....
Rust was still probably right to not expose that at first since memory is supposed be fairly transparent, but Zig forces the user to care about memory, and given that constraint it's nearly free to also inform them of problems. The stdlib is already designed (like in Rust) around allocations succeeding, since those errors are just passed to the caller, but Zig can immediately start collecting data about how people use those capabilities. At a language level, including visibility into allocation failures was IMO a good idea.
Rust was still probably right to not expose that at first since memory is supposed be fairly transparent, but Zig forces the user to care about memory, and given that constraint it's nearly free to also inform them of problems. The stdlib is already designed (like in Rust) around allocations succeeding, since those errors are just passed to the caller, but Zig can immediately start collecting data about how people use those capabilities. At a language level, including visibility into allocation failures was IMO a good idea.