This is true, although a line array only propagates as such when the height of the speaker column is greater than the wavelength of the lowest notes you want to disperse. In the case of two Bag End cabs, which are about 18.5" tall, it stops being a line array below about 350hz. Given that high frequencies from a large driver beam quite a bit, the highs are fairly narrowly focused. The Genzler Bass Array cabinets, especially when used in multiples does disperse as a line array for the mids and highs. It's quite effective.
I'm sure your rig sounds great, but for a true bass line array, you'd need a 30-40' tall stack of cabinets. I've heard this. It's a profound bass experience.