The Python foundation first off, then companies and teams using it. If you're a 1-person team then sure you pick everything, but even then you have to worry about compatibility with other tools. Like, Heroku only got support recently: https://www.heroku.com/blog/local-speed-smooth-deploys-herok... or if you're running someone else's code, maybe you have to figure out your own pyproject.toml

Compare to npm which has been the default installer/manager in NodeJS since forever, so it's totally supported, and any git repo you happen to download has a package.json