I don't see how your version is easier than the sequence of commands in the first few steps of the article, which is basically `pip install flit; flit init; flit publish`. Flit is just as easy to install as twine, but you save yourself the hassle of having to write a setup.py.
Maybe I'm too old-fashioned then. But I like that you don't have any dependencies when using distutils/setuputils with a `setup.py` file, so if you don't distribute your code you're already done. I'm also not a fan of tools that are just wrappers around other tools.
Flit isn't (mostly) a wrapper around other tools - it has its own code to create and upload packages. This was one of the motivating cases for the PEPs (517, 518) defining a standard interface for build tools, so it's practical to make tools like this without wrapping setuptools.