Notebooks serve somewhat different purposes to a raw REPL. They have different cells that run code in nonlinear order (cells are independent of one another) which encourages experimentation of whatever you're trying to achieve. My use case for notebooks is to try out many different ways of doing something and then once I find the right combination, I'll extract that code from the notebook and package it into a Python script. Others also use it to present their code in a literate way, by having code and explanations interleaved.