Doing work on the Zig language would require writing more code than I would likely have to rewrite if I was to use it in the current state and fix the breaks. I want to use programming language without having to maintain it's compiler and without having the compiler devs periodically breaking my code. The fact that they haven't even outlined some subset of the language which is resistant to change basically means that all code written in it has maintenance requirements going forward. By contrast, I can write that same code in C and leave it for a while then have it all be fine when I come back.