Yes, I'm aware of the AAA exceptions. Source, CryEngine and Unreal Engine were around since long before Unity. They represent an extreme minority of games. Obviously the concept of game engines is older than Unity, I didn't think I needed to explain that here...

And even then, CryEngine, Unreal and Source are all engines centered on a very specific kind of game (fps style). There was no serious general-purpose game engine before that, that devs actually used.