Yes, I've definitely been involved in other projects where a single core developer can do a little too much "imposing" of their will. i.e. if they happen to have a personal preference one way or another on things, they not accept or even entertain certain changes.
I wouldn't expect most large, mature projects to be this way (otherwise they probably wouldn't have grown as large or attracted enough of a community!), but it's certainly a problem with some projects.
Projects, of course. Ages ago I quit a notable project partly because of maintainer team politics, so I'm no stranger. But I thought we were specifically talking about language improvement processes of non-niche programming languages (a specific one, even).
I wouldn't be so sure. Search for `site:bugs.python.org "maintenance overhead"` on your favourite search engine.
If you can submit a measurably faster csv implementation to cpython (without breaking existing code of course) I can guarantee it will be welcome whether you’re a first time contributor or not. Not sure about your definition of “more flexible”, if that entails breaking existing code then it may rightfully meet resistance.
Not sure why you’re implying other languages’ proposal processes are about pleasing a single core developer or playing some politics game. Sounds like either you have a lot more experience than I do and hence have been exposed to politics games or anything else non-meritocratic (that I haven’t sensed in CPython development, at least), or you just don’t have as much experience contributing to other languages.
(I'm a bit cranky today. Sorry if I sound aggressive.)