That said, I agree that it'd be moving the goal posts to omit paid libraries.
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I do think we have slightly different ideas of "Systems Programming", or at least what production ready means for that type of language. I think it boils down to the fact that people do a lot more in "Systems Programming" languages than just OS or implementing and providing interfaces. Specifically, people do it for performance and control, which I don't necessarily excludes the use of libraries.
I think the contention here is that people are thinking of production ready for these types of languages in terms of general use, not just the niche you describe. In retrospect, I do think it was a poor way to word it.
I guess I'd probably amend the original comment to say something like "Rust is the first production ready systems programming language that can comfortably (after a learning curve) be used at higher levels".
And then, Ada had a selection of libraries for a long time. You just conveniently forget about the paid ones, so you can call Ada "not production ready".