It's not intended as a joke, and please have patience with me if I'm an idiot.
Imagine you had a program involving, say, chairs. It has things called chairs, which you pass around to functions which take chair arguments. Suddenly, the next version of the language comes out and now "chair" is a reserved keyword, and all your code is broken. To fix it, you have to go through your whole codebase and rename all your "chair"s to "ChairStruct" or "_chair" or something.
I didn't say it was a major world-stopping difficulty. It's just one additional nitpick against OOP for games (added to an already gigantic stack of much bigger problems caused by OOP).
Imagine you had a program involving, say, chairs. It has things called chairs, which you pass around to functions which take chair arguments. Suddenly, the next version of the language comes out and now "chair" is a reserved keyword, and all your code is broken. To fix it, you have to go through your whole codebase and rename all your "chair"s to "ChairStruct" or "_chair" or something.
I didn't say it was a major world-stopping difficulty. It's just one additional nitpick against OOP for games (added to an already gigantic stack of much bigger problems caused by OOP).