Downvote for this web site is a horror movie billboard and zig already has a build system which is zig and that's one of it's neat features.

People are free to knock themselves out with Bazel if they’re into that kind of masochism, but having it as the ONLY way to build your OSS project is a big no.

The problem with "the language tooling is already a build system" is that cross-language dependency chains are a thing. The moment you need a Rust or Zig file to be regenerated and recompiled when a JSON schema or .proto file is updated, you're outside what most of those language-specific toolchains can support. This is where Bazel absolutely shines.