1. All virtualenv related things are not package managers. They're isolation tools. They ensure your application controls its environment.
2. Pyenv, asdf, and others provide the same benefits for versions of Python. They're incredibly powerful tools for those of us who need to support multiple versions.
3. Tools like conda, poetry, pipfile, etc serve to solve dependency management based on how you, as a user want to interact.
Given my needs, I find poetry invaluable (and I use none of its venv integrations). For specific projects I rely on pip, as that meets the goal there.
It could be better, but IMHO poetry and friends have drastically improved the situation over pip freeze.