FORTRAN 77: we pack our data structures into flat arrays and use indices instead of pointers because we don't have pointers or any data structures other than flat arrays

Later langs: Look at this bullshit! Pointers go go go!

Even later: we pack our data structures into flat arrays and use indices instead of pointers because they can be smaller and are easily bounds-checked. Also the borrow checker is no fun when slinging too many pointers around