Listened to a $100,000 plus system in the same room on two different occasions. Once with acoustic treatments placed by an industry professional with proper room testing, measuring devices and the like. Took it all down and the music sounded better. It just did.
I have had dedicated rooms with all manner of acoustic treatments and my current living room with two diffusion treatments sounds far better.
Also had another interesting experience this past month. I first placed my speakers far away from room boundaries and did all I could to remove the room’s impact on the sound. Sounded great. I then placed my Fyne F704 speakers in the room corners just one foot from the side walks and some 4 feet from the wall behind them. Strong toe in. The room was more at play now influencing the sound far more. Guess what? It sounds even better this way.
I can confidently say acoustic treatments are not always needed and won’t always sound better. I can also say acoustic treatments can indeed help improve the sound of your system. No broad brush answer or absolutes here. Depends on the room and your furnishings etc…
Don’t accept any “common wisdom” and simply experiment on your own. Trust your ears and preferences.
I have noticed that absorption panels often hurt the sound. This has been experienced in my last two rooms. I no longer use them, but instead use a bit of diffusion on the front wall. This is only my experience and you may find them advantageous. Again, it all depends on your particular space, furnishings, gear and sonic preferences.
A dedicated room is not always better sounding. An acoustically treated room is not always better sounding. Real fine sounding systems do reside in shared living spaces. Also, treated dedicated rooms can also sound absolutely stunning. Your mileage will vary on this so experiment for yourself!