Ruby and Go both adopted extensively from Python, but both rejected the process described in OP of designing a language by iterative experimentation to determine how coders would experience design choices. Instead, each relied on the judgment of a handful of experienced insiders. "*I* know which parts of Python are good and which suck; no need to run my ideas by a few dozen coders before committing to them."

Perhaps not coincidentally, neither has displaced Python. Go obviously had powerful backing from Google. I believe Ruby had enormous tailwinds from the need of the Java community c. 2005 to find an interpreted language, but not one with as mature a community as Python's was at the time. Ruby was at the sweet spot of "usable, but with plenty of niches left for alpha geeks looking to write blog posts."

Finally, I hypothesize the Amber-Brown-batteries-included and walrus-operator kerfuffles demonstrate the limits of managing infrastructure such as Python with the RFC / Usenet model.