Indeed if you don't want to manage everything yourself I don't think there's a need to use Zig. The whole pitch is making everything explicit and not hiding control flow. And I do think that limits its usefulness to smaller-scale codebases.
Writing quality software doesn't require much from the programming language until your codebase gets very large and you're collaborating with a ton of people. If I'm expecting a codebase to grow to a large scale I'm not reaching for Zig for that. I don't trust _myself_ to keep that much Zig code tidy and correct let alone a big mob of developers and agents :)