When you fire the gun the hot gases burn up all the oil in the barrel. So at least you have to replace the oil. Otherwise the barrel may rust.Dirt and sweat may remove oil from the outside .So clean it after every use ,at least a light cleaning and oiling !
Light cleaning and oiling won't hurt -- but there are too darned many guns that go hundreds or even thousands of rounds without problems or rust to make a sweeping claim.
Many of us learned about cleaning firearms from our Dads or Granddads -- and they learned from the US military, during WWII. Back then, the powder used was corrosive, and if you didn't clean the weapon rigorously (at least in some climates), the action could rust shut pretty quickly. That is no longer the case.
Nowadays, if one of my guns seems extra dirty, I'll wipe out the chamber with a bore-cleaning pad after a range session, and then run a bore snake down the barrel a time or two, using CLP. Then I'll put the gun away. My guns won't look all that different from one that's been detail-stripped and given given a bath...
Clean if you want to, but I've heard more than one gunsmith say that he's seen more damage from too-intense and too-frequent cleaning than from a lack of it.