Your argument seems to be "just write good code instead of bad code". My argument is "the best way for good code to exist is to enable and support multiple options". Because if you have only one option and it's bad then you're screwed with no recourse. C++ and Python have, imho, many horrible API designs and we're stuck with them forever. This is stagnation.
Rust has a good standard library and also a large community of libraries. Sometimes those community libraries get promoted to std because they're strictly better. Sometimes the std version of hashmap is slow because std insists on using a crytographically secure hash when 99.99% of use cases would be better served with a less secure but faster hashing algorithm.
Like many things in life the ideal scenario is a benevolent dictator that only makes good choices. In practice the best way to get something good is to allow for multiple choices.
<insert parable of pottery class graded on quality vs quantity>
