> And yeah, sure, some folks will respond with "but go isn't OO", but that's silly. Modelling polymorphic behavior across different data-bearing objects which can be addressed as implementations of the same abstract type quacks, very loudly, like a duck in this case.

It's less "this is not OO" and more this is not inheritance, which is why a lot of people are saying you can find more elegant solutions (like this) rather than use inheritance for no clear benefit.