That's because it IS a drop-in replacement for Argparse
Gooey began its life as a monkey-patch of argparse. GooeyParser came along later to extend the limited argparse API with additional options that made specifying more complex GUIs possible.
I opted to leave that detail out of this one as I was trying to focus on the larger general capabilities, rather than the Python specific implementation details.
I would include it, at least as a footnote/sidebar! It will be a huge selling point for python projects that already use argparse, and there are a lot.
