Perplexed on how single driver speakers can cover such a large Hz range

And there is that little thing called MASS and the other one ACCELERATION (btw, they don't like each other much). So yeah, and can CLEARLY feel the OP. Imagine the force needed to shake that massive cone 10,000 times per second back and forth. Obviously, something has to give. 

I’m a longstanding fan of single driver speakers. My main speakers are an upgraded pair of Voxativ speakers, i.e., their driver was upgraded to a more power magnet and a custom horn created that was tuned for upper mids. I’ve come to experience that the cabinet design greatly influences the depth for the lower frequencies. Single driver speakers are thin on deep bass, but I love their speed. The preferred dynamic range was achieved only with the inclusion of a pair of subs inserted into the 2 channel system. BTW, Voxativ now has single driver models with with built in subs. 

Also have to mention  the Walsh driver solution to  keeping the sound coherent across the hz specturm.    Their composite cone is inverted in the cabinet and the sounds rolls off the back of the cone in a 360 degree fashion (they attenuate the back of the speaker sound via sound absorber for better imaging)  .  As the signal from the voice coil travels down the speaker all of the individual hz responses are reproduced and come off the cone in parallel so that the result is a completely coherent line source for the sound (CLS) .    Another advantage of this solution is  a very large sweet spot in the room .  

@ronboco See video linked below starting at 6:30 where Jon Ver Halen, Cube Audio’s US distributor, explains the unique engineering solutions incorporated into their Nenuphar loudspeakers to overcome the frequency extreme limitations of traditional single driver designs of the past as well as several other improved aspects of their design:

https://www.youtube.com/watch?v=Ma7dvPyr5T0&t=1s

My brain hertz just thinking about it.