Tony Barbetta build some great speakers. I hate several sets of them. He was most likely referring to keyboards--such as synths, pianos, Rhodes, organs.
I consider my "sound" a full band, or combo. It consists of bass guitar, lead instruments, drums, and vocals. The fact that it is generated by a keyboard doesn't matter. I still need amplification for a full band!
Not so long ago, it was essential to use big speakers if you wanted really great bass. Not so any more! Technology moves on and you can get great bass from smaller speakers, and still cover a lot of area with them. I've been happy with 10s, 12s, and even 8s sometimes. As a matter of fact I can get great bass from my headphones! It just isn't very loud except for the wearer.
It all depends on the size of the venue you want to cover!