> A serious C++ engine with a "data oriented" design would have the same arrays of primitive types and dumb structs as its C counterpart, merely dressed as std::vector or std::array
Yeah, I agree. Including the "full C++" to the comparison was just trying to avoid having to argue about which is the "right" subset of C++ for engines, which is somewhat besides the point. The main problems I have with modern, data-oriented C++ are mostly compile times, slow debug builds and non-trivial reflection.
Some don't mind those, and be happy.
For example, the paragraph about loading and saving game state postulates "using the ideas of polymorphism and encapsulation", automatically throwing a lot of pointers and vtables in the way of reading and writing a binary blob like in the C engine. A serious C++ engine with a "data oriented" design would have the same arrays of primitive types and dumb structs as its C counterpart, merely dressed as std::vector or std::array.