Pip is fine, it depends on your goals. I've found requirements.txt less enjoyable to maintain for several reasons – you need to separate dev, test dependencies on your own time, there's no notion of a lockfile for transitive dependencies (`pip freeze` notably doesn't separate actual dependencies from transitive dependencies). pip is also darn slow at installing dependencies once you hit a certain scale, and poetry outperforms it pretty substantially.

Poetry does I expect a package manager to do, and does it well, especially when working with a team of developers on an application versus individually. There's not a compelling reason for me to use pip directly as a less functional alternative.