I don’t claim it to be common practice, just saying that it exists. That said, it may be “niche” in the grand scheme of things, but by no means do I think it’s small and insignificant. If anything, such codebases are typically foundational libraries in the giant stack of cards most other software engineers build.

See also antirez’s article about code comments https://www.antirez.com/news/124 You’ll notice how some of the snippets would’ve easily failed your criteria.

I think comment ratio could be a fairly misleading metric. There are programs out there that requires a lot of context upfront that distills down to just a few lines of code, and especially those that are more academically interesting.