I think DS-21, AJ, & I are just agreeing with Siegfried Linkwitz that perhaps room treatments are being overemphasized and in some cases over dramatized.
If your room has an eco, then you do need to do something about that.
But you don't need to "treat" a room just because some people think every single room needs "treatment".
Exercise moderation. As someone already says, what are you trying to treat or improve?
If you are trying to treat an eco or some adverse sound effect, room treatment is necessary.
But not all forms of treatments are the same and not every room needs treatment.
As DS-21 says, not everyone needs "panels". Some people just need more carpet, curtains, drapes, sofas, etc. Siegfried Linkwitz says the same.