That up to 70% of what you hear in a particular system is the sound of the room
Absolutely!! Until you treat it, you can't hear anything.
What I think happens is that over a long period of time, Audiophiles learn to hear past the room acoustics, but it's like watching a movie in a smoke filled room.
I can also say that I've gone through a lot of hardware, but I've NEVER played merry go round with my room acoustics. I've only added more pieces.