You can use Matplotlib for plotting the graph.
Matplotlib is a plotting library for the Python programming language and its numerical mathematics extension NumPy. It provides an object-oriented API for embedding plots into applications using general-purpose GUI toolkits.
Here I also haven't saw anyone plotting complex graph in python.
Yes, Because sololearn hadn't covered the topic related with graph in python(or in any other languages) But now sololearn has add ' Machine Learning 'in their learning section so may be in future we can see such graphs.