Most rooms don’t need acoustical treatment.

Why?  Because acoustical treatments presented are in virtually empty rooms. Unrealistic.

my rooms have furniture and clutter.  These rooms don’t really have a need for treatment.  It’s snake oil, voodoo science.  
So why is accoustical panels gonna help?  No one can answer this, most have no clue.
Ampa style setups need close to nothing. No back wall and tapered side walls and ceiling, no reflection points..

Setting up kitty corner, eliminates a lot of the normal treatment ideas and again the reflection points diminish. Room decay rates are much quicker.

Clutter counts :-) There are ways to reduce the UGLY as$ wall treatments diffusers, dust collecting stuff. Foam is hard to keep clean.

CURTIANS work and look the best to me..

It's easy to tune a room and liven it up just a bit with a curtain pulled open or closed a little more.. No studio looks for me.. 

"So why is accoustical panels gonna help?"   

Are trying to say :

So, why are acoustical panels going to help ?

Truth, but only if you want to justify your room multipurpose optimisation. However, if you have dedicated room for critical listening, the room where you want to dissolve in your music without distracting factors, you’ll need treatment. 

It's 'sand them all'. 

Back in design school, I was in line in the shop to return some tools. A friend of mine walks up and asks the guy in front of me if he should sand just one of the pieces of wood for a project.
The guy responds by saying 'just sand them all'.
Then they both pause as a light flickers in their nerdy eyes before they burst out in laughter.

My name is Sandamal. It's a perfect phonetical pronunciation of my name. And once again, as it has so many times, my name has betrayed me.

Bottom line it does not matter. We all spent serious money on our systems yet The chances of even 1% being the same is rare. All that matters is our own ears and the preference of sound that we prefer or are reaching towards. I have heard inexpensive systems that sound great and really expensive systems that do not. I am an advocate of some room treatments. That is because it sounds great to me and several other people.