I think you identified the selling point of OOP, it's easy to reason about it and logically it makes sense to human because we do think in terms of objects (the user, the order, the item etcetc) and responsibility segregation (User->login(), Order->fulfil(), etc). To your example of just launching intellij and using java (or ruby or whatever) to build something, yeah it works and it works fast and it's easy to add new features, and it's also easy to end up with a >3k loc User class in python that no one can touch (true story).