Like, what does "avoiding hidden control flow" even mean? What value there is in having no convenient facility to do buffered I/O? Hidden buffered output wasn't really a problem even 40 years ago, it's one of those things everybody needs and those who don't are well aware of how to use the primitives and do it properly.
But let's be clear, I have nothing against Zig, I quite like it from a language nerd standpoint and I think it's very neat - I just don't understand what is the intended target to be honest. If I'm not looking for a safe language, C is fine, and for all its warts and bullshit C++ works with basically everything under the sun. If I want safety, there is Rust which basically already enforces the same patterns you need to follow to get safe C/C++ programs anyway - in my experience, 99% of the time someone whines that the borrow checker is stopping them from doing something, it's because they are making a massive logic mistake and they didn't notice there's some hidden unsoundness (like pointers with unclear lifetimes, etc).