The easiest way to explain why electrostats sound better than conventional speakers can be seen in the pictures below.
When we drop a pebble in a pond, waves spread the same way sound does. As you can see, the wave spreads without interference from its “point source”. In order for the sound to remain coherent in time and phase when it reaches the listening position it’s important to eliminate any interference patterns, both reflective and those created in the crossover regions.
In picture 2, we see what happens when a second source of waves is added. This is what happens with a 2-way speaker. The sound waves interfere with each other in the crossover range, 
smearing the stereo image. Clarity and resolution are lost, frequency response becomes disrupted at the places where the waves intersect, creating peaks and valleys in the response.
In picture 3, we see how multiple waves make things even worse.This is what a 3-way speaker does, it creates many more overlapping sound waves, again resulting in a loss of clarity and resolution, with further damage to linearity. The more drivers 
a speaker has, the worse it sounds.
All conventional speakers compromise clarity and resolution for the sake of covering the full audio bandwidth of 20 Hz to 20 KHz. The use of crossovers does not solve this problem, they are the cause, the frequencies above and below the x-over point are subject to damaging interference, along with the rest of the audio band once these sounds begin to bounce off the walls of the listening room before arriving at your listening position.
In nature, we hear the direct sound first outdoors, a survival skill learned by our ancient ancestors to locate danger. Upon hearing the crack of a twig breaking 75 yards away, we could quickly identify and locate the source of danger and skeedadle the other way.
Our brains ability to locate sounds in space accurately is put to good use when evaluating a speaker system’s ability to precisely locate voices and instruments in space, create a realistic and stable stereophonic image of the musicians and singers on stage. This ability is fundamental to how an audiophile chooses a speaker system, does the speaker actually come close to a sealed headphone?
When it comes to precision stereo imaging; clarity, and resolution, nothing beats an electrostat. When the listener is equidistant from each speaker as the speakers are to themselves, the direct sound-field reaching the listening position is +5 dB louder than they reflected sounds, providing the listener with all the localization cues the recording engineers embedded in the mix. The directional dispersion pattern is just like in nature, directly from it’s source, so you can locate where the sound is coming from before the reflections arrive at a much lower level.and later in time.
With conventional speakers, the direct sound reaching your listening position is arriving later in time and lower in level, with the ratio of direct to reflected sound more balanced because conventional tweeters have a wider dispersion pattern and because dynamic drivers lose a lot of energy on the way to your ears. The further back the listener, the more muddled the stereo image becomes as a result.
Understanding how sound waves travel and interact with the room is the first step to becoming a discerning listener.