Who said “ flat freq response “ is the best?

This discussion begs this question: would two different speakers with identical frequency response curves sound the same in your room? I'm betting the answer is no.

"Try throwing pillows and blankets on the floor between and behind the speakers as an experiment. "

Don't forget the fake plastic plants behind the speakers...!

Dog beds work as well!

Big, hairy Tibetan mastiffs work even better. 

Yes. I’ve said that. Components should be designed to be as flat as possible to be faithful to the original recordings. From that point, all hell breaks loose with rooms, our ear/brain function, personal taste, probably sunspots for all I know. Without flat component response, we have no standard for comparison. What’s to keep products from varying from one to the next?  What good would it do to audition something if the example you buy is different?