Oh no that is very correct altough Tier systems make it easier to understand where decks can be put in terms of easy to play versus hard to play. It's not like Orks and AM can't win from SM or Eldar but I do always feel there is a slight disadvantage present in AM and Orks for no reason. A part of this is due to how much these two faction rely on Supports who currently don't cause additional income. The card closest to that is Ammo Depot but the way it's worded requires you to also play a load of cheap cards (ideally with Ambush or that are Event and as such can be played during multiple phases).
The great Ambush cards or Events are not overly present in either AM or Orks...