The author is correct that you want a tool such as flit or poetry which will work with pyproject.toml. Setting up a basic package will be no harder than using setuptools, and it is much more future-proof. You won't have to copy-paste some other crufty setup config either.
It is fair that you don't need all the external tools in this tutorial. In particular, using make is very silly since you can configure different linting and testing workflows directly in pyproject.toml, rather than pull in a whole other system which only works decently on *nix. Poetry also removes the need for tox.