Naim speakers are designed for out and out quality at normal listening levels, and (most of them) aren't really designed to go anywhere close to disco sound levels.
DBL's and NBL's (great speakers) aside, which could play at ridiculous levels without strain.
You do state (most of them), so technically, I guess there would be some truth to your statement, but it still doesn't make it OK. I have compared other very high quality speakers that have no trouble playing at elevated levels and absolutely do not break up or bottom out when paired with the proper ancillaries.
If you do not believe what I'm saying, audition ATC, Dynaudio, Focal, Sonus Faber's, Magico, Wilson, Triangle, B&W, and the new Spendor D series speakers, to name a few, and crank them!!!!
These speakers are all what I would consider, at the very least, equal in quality, or designed for out and out quality, as you put it. The difference between those speakers and Naim, if what your saying is true, were meant to be played at ANY listening level.
Kind of a moot point I know, since Naim doesn't manufacturer speakers anymore. Could be one of the reasons they were never great selling speakers.