There are many versions of this available as PA cabs. There are none marketed as bass cabs but without a doubt some players are using them. I don't see it being a bass player thing, as we generally prefer the least complicated arrangement. Besides, one need not have a small box at ear height to hear mids and highs. Tilting a standard cab accomplishes the same thing.
Which proves the point. A common assumption is that midrange drivers are paired with woofers to extend the high frequency response. That's true to some extent, but the main reason for using midrange drivers is they deliver wider dispersion than woofers. That's because they're smaller. Tweeters are smaller than midranges for the same reason. Time was when you had to use a fifteen to get enough cone displacement for the lows along with a midrange for dispersion in the mids. That hasn't been the case since the turn of the century.
Current state of the art in driver design was realized closer to 20 years ago. What's changed since then is more and more sources are producing state of the art drivers.
Of course not. But a fifteen cannot realize the dispersion of a ten, or a twelve, which is their primary advantage, while still being able to deliver enough output to fill the stage, leaving the heavy lifting out front to the PA.
That One 10 defines physics. Moving air isn't just an expression, it's how speakers work. A high quality modern ten with 8mm excursion capacity will move as much air as vintage fifteen with 3mm excursion.
One watt is the rate at which electrical work is performed when a current of one ampere (A) flows across an electrical potential difference of one volt (V). Period.
Could be, but plugged in? the last time I saw ZZ Top they had two dozen or so Magnatones on the stage. I asked their road manager how many they were actually using. He told me Billy and Dusty were using two apiece, the rest were 'eye candy for the kiddies'. 😄