There's a reasonably unambiguous way to measure how "opinionated" a language is, which is to look at the size of its runtime necessary to run programs in that l

There's a reasonably unambiguous way to measure how "opinionated" a language is, which is to look at the size of its runtime necessary to run programs in that language [1]. C's is not huge, but it is necessary and non-zero. By contrast, many other languages have huge runtimes. There are some languages that can get smaller than C. Assembler, obviously, is basically the smallest. Rust does have a default runtime, but it's thin, and most of the rest of it can be shut off. Still, it's not a long list of languages that are less opinionated than C. [1]: If you want to get really technical, this is "relative to the hardware it is running on". C gets a bit of a bonus here because the hardware has over the decades actively targeted C. Particularly visible in the processor's support for calling conventions, and manipulating a "stack" so natively. (While a stack is really, really convenient, it is not, strictly speaking, necessary for programs to be structured that way.) But for the sake of simplicity I'll ignore that for now.