I could use a coffee! It fuels consultants, editors, domain registration and so many other things required for PySimpleGUI to be a thriving project. Duplicating Excel in every detail is an example of something not well suited for PySimpleGUI. It depends on the details of your program. It's difficult to define exactly which programs are well suited for PySimpleGUI and which are not. By definition, PySimpleGUI implements a subset of the underlying GUI frameworks' capabilities. Some programs are not well-suited for PySimpleGUI however. While the architecture is simple to understand, it does not necessarily limit you to only simple problems. Your code is not required to have an object oriented architecture which makes the package usable by a larger audience.
Further simplification happens by changing event handling from a callback-based model to a message passing one. The window definition is simplified by using Python core data types understood by beginners (lists and dictionaries). Transforms the tkinter, Qt, WxPython, and Remi (browser-based) GUI frameworks into a simpler interface.
