My Teacher Always Says: Do Your Project With Knowledge That Your User Is Stupid

Developer: "Tea bags are so intuitive they don't need instructions."

End user: *dunks entire tea bag, wrapper and all, into hot water*

And that's why we write documentation for even the most "obvious" features. Users will find ways to break your software that you couldn't imagine in your worst fever dreams. The line between intuitive and incomprehensible is thinner than your project deadline.