Matplotlib is necessary because it is very necessary because while assesing the perfromance of your machine learning model you need to visualize that the model is working perfectly and if it not then you need to change the parameters
Here are some functions basically, plots which are highly used to while machine learning so as to analyse the data
There are various properties of the graphs that have been untouched, it would be fun if you would play with them Also going through the documentation of the library would be helpful. Access the link here