AP and essences, absolutely. I can pretty much guarantee that every timegated grind for basic character progression rather than more minor ancillary rewards would have been the idea of the bean counters.
Island and Warfront, probably not. Those weren’t really pitched to us as MAU bait, and Warfront was pitched as a PVP thing. Remember, we were even all on board with them until they rolled out and ended up being, respectively, impossible to explore and unfailable facerolls full of waiting. That strikes me as an actual dev idea that ended up lead ballooning.
Azerite system in general…mixture probably. I’d imagine Ion and co. came up with the main scaffolding and failed at balancing them, but the marketing goons are most likely the ones who shoehorned in making them impossible to obtain outside of timegated loot boxes.