There was a time when aluminum bikes were new but before the parts likely to bend were replaceable where many a bike owner had to buy a new frame due to misadventure. You can only bend aluminum once, then you’re done. When they started making cogsets with more than six gears they went with axles about half a centimeter wider, and you had a similar conversation. You can have the longer axles but you can’t change your mind after. They have to bend the stays slightly and there is no going back after that (and let me tell you, the mechanic got really quiet when they did the bend. You want to get it just right and every bike and every frame size is different. You pull until you feel the metal just start to give and just after that is your 5mm)

Steel frames could often be rebent. But they’re heavier and they don’t like moisture. And their strength to weight ratio is only about the same as wood. Probably also bad options for firefighters.