If a good job is done matching speakers to room acoustics, need for treatments can be minimized. Sometime not even needed. You might even find less is more in some cases.
In a lot of these threads people say without the room being treated
It's a waste of money to upgrade you're system. The problem is I don't think most people know how to treat their rooms. I really think it takes a professional to know how to treat a room. Sure you can play around with it if you like but it could also be a big waste of time and money. And I know hiring a person to acoustically treat a room can't be cheap. I wonder why more people don't discuss this subject and make recommendations on who does this kind of work. When I look at the big picture this makes the most sense.