Who said “ flat freq response “ is the best?

There are a few subjects being discussed here: 
Flat response from Equipment and speakers
Flat In room response. 
If you think about it,  when the recording is done,  are they done in perfect rooms?  Carnegie Hall,  Studios, Restaurants, Church's.  Every recording will reflect the room that it was recorded in,  then our room has an effect again on what we hear.  The only way to hear the recording as it was done is with a flat room.  Ideally, all recordings would be done in a perfect anechoic chamber and our rooms would be the same, but its tough, shoving a symphony in a chamber. 
Next, for Equipment,  I do believe that it is important for our equipment to be producing a flat response.  That is the only way to faithfully reproduce the recording, assuming that we can have a perfect room.  I believe that it was @kalali that posed the question, would 2 different speakers with identical response curves sound the same in the same room.  I can answer that, I have built many speakers and have come EXTREMELY close in duplicating response curves, but I can tell you for a fact, not opinion that different driver materials sound different and on crossovers, even using the same slopes and same type of compensations or no compensation that crossover parts still sound differently from each other. 
Overall, my contention is Absolutely,  you need to come as close as possible to achieving a flat response curve on your electronics,  in your speakers and in your room.  If that is achieved.  It is then that you get as close as possible to creating that all allusive "Live" sound that we all work so hard to achieve.  Plus when things are acoustically flat, it does help hear so many other design presentation differences in amps, pre's, cables etc. 

@douglas_schroeder
Hi Doug, although I do agree that there are several speakers that are nice to listen to that don’t necessarily come close to that ruler flat acoustical challenge. I have to disagree on the idea that seeking and building toward that flat response a fairly fruitless effort.
All Amplifiers and Pre Amplifiers come VERY close in a flat response, but as you know, One can and will sound much different than another. The flat response is no more than the idea that everything starts with a level playing field, but yes, you are absolutely correct that a totally flat response curve does not at all guarantee excellent results and/or a system can be satisfying with all kind of things being out of wack.
@ieales
As far as the Phase discussion, there are a ton of threads on Phase (not to be confused with phase angles), but phasing affects imaging and sound stage much more than it does frequency curves.
Tim

@geoffkait 

For everyone,  geoff is accurate,  speakers publish their spec's with a frequency response and a variance within that response. 
Exceptionally flat speakers are normally rated Plus or Minus 1 db.  Anything that is typically more that plus or minus 3db is normally not considered audiophile,  although that certainly is not cast in stone. 
Today,  Many speakers are rated at a flat 2.83v input rather than 1 watt 1 meter.  For accuracy,  you need an accurate impedance, an accurate response curve and an accurate sensitivity rating.