If they don’t have bad code it’s because it’s a bunch of enthusiasts that are good at coding. Realistically I’m sure there’s even now examples of code that would be considered “bad” in any of those languages.
Certain properties are of course enforced so it’s impossible for a project to do certain things that make the code harder to read. On the other hand, humans are so creative that I have a hard time imagining that, given time and a wider mix of talent, you’ll still have code hygiene issues. Maybe not the exact problems that another language might have, but certainly your own flavor will be developed as developers have less contact with the core language enthusiasts that establish said best-practices..
Again, happy to be proven wrong but I’d like at least anecdotes or some kind of evidence rather than a theoretical argument from first principles that completely ignores the human element.