This is a common misunderstanding. Structural programming like this is clearly similar to what we think of as OO. But it existed before OO and is still heavily

This is a common misunderstanding. Structural programming like this is clearly similar to what we think of as OO. But it existed before OO and is still heavily practiced in non-OO languages such as C. The main feature that OO added to this was dynamic function dispatch via inheritance. The specific function that gets called at runtime depends on the type of the struct. Inheritance has proven powerful but often results in confusing code. The development of interface-based (non-inheritance) dynamic dispatch in COM and Java, and later embraced by Go and Rust, shows that we can get what is arguably the primary benefit of OO with a flat structural approach.