The article mentions file_operations, but ignores that it has what would be a static member function in C++ in the form of ->check_flags(), which is never in a vtable. The article author is describing overlap between object oriented programming and something else, called data abstraction, which is what is really being done inside Linux, and calling it OOP.
You can implement OOP in C if you do vtables for inheritance hierarchies manually, among other things, but that is different than what Linux does.
