I (Bazel SWE at Google) agree with the too much flexibility being a problem. It's difficult for tools to work on complex Starlark code, so we encourage more copy and paste especially in BUILD files. But I don't think Blaze could have scaled to Google's needs without some amount of programmability. It's not just that it "looks tighter with a macro", when you have a rule that gets used to create millions of targets, you can't just copy and paste. You need to be able to systematically change it.