You know, for all the difficulty in defining the term "engine", I think the term "golden deck" is even more contentious.
The problem with a "golden deck" is that it was originally defined by pointing to a particular deck: Bishop, Silver, Silver, Gold, Province. And that might have made sense in the days of Prosperity, but I think by this point it's not very common, and not very good either. I'm not sure I've ever made a deck like that. So the question is, do we expand the "golden deck" label to a larger set of decks? Or do we just think of it as a narrow category, like the Hermit/Market Square deck, or the classic Hunting Party deck?
Some people seem to define "golden deck" as one of those decks that does the exact same thing every turn. So, like, if I have the bishop thing, and I opt to buy Gold instead of Province one turn in order to manipulate the Province supply, it's not a golden deck anymore? What if I added a few Chariot Races? Honestly this definition is just weird to me. In my play group, we use "golden deck" to describe decks that score points without adding dead cards, but maybe that's weird too.
I don't know why the term "golden deck" has such a hold on us at all. Maybe if people had just called it the bishop deck, we would have forgotten about the very concept by now.