I see no reason pure modularization wouldn't achieve the same thing. In fact, that's what I took OOP to mean for a long time. But it doesn't need to be bound to the data, or mutable as in not functional. If member functions return objects and data, they can be used in a functional approach and to construct polymorphism or inheritance through currying.

Are the OOP language features the essence of OOP? 'Everything is an object'? Multiple inheritance?

if an object can be reduced to a symbol like a void-pointer to data or a function that returns data and this object can be related to others on a graph, then that's still general enough.

Imperative Programms as well as Object models can be well organized in graphs. The CPU or bytecode doesn't know about objects anyway. So it's an abstraction and you need to applay that in a moderate fashion, depending on the complexity of the problem, so for simple or efficient procedures imperative style is not to be replaced by OOP. fopen, fread etc. all are abstractions of underying system calls, but depend on speed, so light OOP is a good fit there,