You are looking at this from the wrong perspective. If you are fine with automatic allocations and RAII like you have in C++ or Rust, or with a garbage collected language, there is pretty much no reason to even look at Zig.

Zig is a language to use when you do need the control, mostly because of performance reasons. And once you are in, you start thinking how to manage your allocations and arenas are the logical outcome, once you notice that your application has scopes that can be destroyed at once.

If you need an argument why arenas are better than RAII, then you likely don't have the performance needs to even consider using Zig, because outside of performance, arenas are not better.