It is like saying "why do C++/Rust people don't want a garbage collector?", or "why do Haskell people insist on function purity?". A GC in C++ and Rust would make things much easier, and a few impure functions would likely make Haskell more practical, and then, if Rust let go of all that "memory safety" cruft, it would be much easier to write one-off scripts and prototypes with it.

Languages have opinions, that's why there are several of them and they are popular in some applications and not others. And Zig opinion is to be explicit so RAII is out, and the language does push you into avoiding allocation when unnecessary, as a side effect of not giving you the "easy to use interface" you want.

This makes it particularly suitable for fields like embedded software where you may not have malloc/free at all, but may be less so in a highly dynamic environment, where you may be better served with a GC anyways.