The difference here is that there aren't C programmers who don't know about Rust, and since they're writing C, they have reasons they aren't using it. The same is not true of Zig. Some of the reasons not to be using Rust may be applicable (no specification comes to mind), others may not be.

I do agree that, on an even playing field, Nim should be considered when any of Rust, D, C++, or Go, are on the table. This is less true of C, and therefore, Zig. There's a difference between something being possible, and something being easy and pleasant.

There are also people using C, who really should be using some other language. Which is, in that case, probably not Zig. When you understand that C is the rational choice for some sorts of programming, you'll understand why Zig is a contender, in a way that the other languages we're discussing are not.