More accurately speaking, Zig helps spatial memory safety (e.g. out-of-bound access) but doesn't help temporal memory safety (e.g. use-after-free) which Rust excels at.

Which is something that even PL/I predating C already had.

As long as you are using the "releasesafe" build mode and not "releasefast" or "releasesmall".

> Because it never achieved mainstream success?

And with this attitude it never will. With Rust's hype, it would.