I think it is more of a frequency response issue. Warm/euphonic sounding speakers emphasize the lower midrange and roll the highs (in fact, studies suggest people prefer speakers with roll the high starting around 14 Khz), and in the context of stereo speakers it can give the sense of body to instruments, and a sense of fullness to the sound. The compromise is made to compensate for limitations in stereo reproduction. Conversely, if you have multiple speakers, by design you are addressing some of the limitations of stereo reproduction, the sense of body and fullness of the listening environment is created by rear and side speakers. However, if you now have multiple speakers designed to be euphonic, the overemphasis of particular frequency ranges becomes more apparent.
Dunning–Kruger effect - a cognitive bias where individuals exhibiting poor ability suffer from an illusion of superiority, due to their mistaken assessment of their cognitive ability. That is, a high level of incompetence prevents such individuals from cognitively recognizing their own ineptitude. Yeah, I know...the irony.