Citing poorly designed xovers as proof is pretty disingenuous, tweeters with simple cap only will produce high levels of distortion due to low freq drive and excursion , the difference is very audible , not to mention impedance mag/phase. You can subjectively like a particular setup without reaching , to state a single driver systems dont have phase rotations is also wrong , a well designed xover will produce no midrange colorations or compression and will produce more SPL with less distortions , its only disadvantages, is xover insertion loss , extra cost, more complicated design to work and dynamic compression if poorly selected parts are used , it will require "power" so with flea power advantage single driver with whizzer cone, well , maybe , Small cones also lack percussive energy or "weight " this lack of weight may or maynot impact your liking , it does color the sound and since sound is pretty subjective, thats ok , the science, not so.....
Its also easy for me to hear the splash with dome tweeters from poor xover design with simple cap, i can also hear what it does differently and why some will like it , same with single driver, will you like it , apparently some do ..
enjoy what the single driver does, the xover can be your friend for a different journey....
Regards ...