What I'm saying is that bundling a specific Python interpreter and separate package environment should be the default. I'm not sure what it'd take to get there for a vanilla python install. But more system-level interpreters is not it.
Currently, the way I know of to do that is pyenv . And I know PyCharm let's you pick a python version when you start a project (though I don't use pycharm so that may not be true anymore).
though ironically in a very unpythonic way there are a bunch of these python environment creators. (conda, virulenv , pipenv....)
pycharm lets you select you favorite, which is pretty nice.