The discussion revolves around the decision to use Scala in Mill, a build tool, compared to simpler alternatives such as Python or Starlark for configuration management. Critics argue that using Scala may add unnecessary complexity and hinder readability for those unfamiliar with it. They suggest that traditional configuration languages could be more effective due to their straightforwardness despite being verbose. Concerns were raised about determinism, hermeticity, and ease of understanding in Scala versus a static, simple language like Starlark, which allows better control over builds. Additionally, the use of a functional programming language for configurations may burden users who prefer clarity and maintainability.