You got one big file with code. For a game like Call of Duty, will be over a million lines of code used. You can imagine it will be a mess, if you don’t structure this well.
You want to change the characteristics of weapon. If there are no objects, it should mean that all code blocks exists in one file. For a game as Call of Duty, you can have over a 10,000 methods
Same as you write a encyclopedia without chapters. People will think it is an over kill of information and never read it.