Yes...I agree, as experience has taught me that it is a Big No No to have more than 1 set of speakers in the same room for "Optimal Condions". Many years of selling Stereos at the Retail level in "Sound Rooms" convinced me of that! The magnatude of difference, understandibly varies with each instance, but having 6 or 10 pairs in one room is definately worse than one pair. With regards to 5.1, 7.1, 11.1 etc... well that is an A/V thing and definitely NOT a 2 Channel Hi Fi thing. I learned early to "have a minimal number of speakers in my Stereo Room" for the Best Outcome. (Oh yeah... generally speaking, having Musical Instruments in your Stereo Room is also Detrimental for Audio Accoustics... Guitars, Drums etc... sorry but it is true. They look Great but are Not Helping with The Sound).
To each his own but... I have only one pair in the Music Room (at any one time) and have eventually went so far as to reduce my TV Room to 3.1... never been Happier.
YMMV