Speakers don't sound better because some marketing dude decided to throw a label at em.
In order to accurately put out low frequency sound w/ long wavelengths, you will generally want a large and relatively massive speaker. In order to produce the high range you want something small in mass.
Most hi end speakers of conventional design utilize at least three types of speakers:
tweeter - highs
mid range - self explanatory
woofer - lows
Each is pretty darn good at making the sounds in the targeted range and pretty poor making sounds in the others. If you have ever pulled up to a car with several amplifiers and the bass cranked up all the way, you have heard what happens when one tries to make loud low frequency sounds, you have heard a speaker trying it hit frequency ranges for which it is clearly not suited.
Most of the sound you will hear from a speaker is in the mid range so, yes they get fuddled a bit when trying to hit highs and lows. A mid range speaker that attempts to hit produce full range of sound will get fuddled because it's trying to make sounds beyond it's capabilities.
Usually a mid range speaker will be set up to ignore the extreme lows and highs to avoid such conditions.
woofers on left (conventional)
mid-range bottom 2/3 on right (non-conventional)
tweeters top on right (non-conventional)