Nobodys mentioned the reason subs got started in the first place.
It was thought that if you could produce just bass from a single speaker it would improve the sound, because bass is nondirectional, and this would lessen distortion in
the mains, since they could now produce only treble and midrange.
In other words full range is a bit much for a speaker, you need a sun that is specialized
in bass, and a pair of mains that do mid and treble, and do it even better because
there is no distortion caused by bass.
That was the theory, anyway.
So, according to this theory a system with proper crossover and a sub should be more accurate.
In theory